Scary stuff — AK-74 after firing corrosive ammo and not being cleaned for a week.
Image courtesy ADCOFirearms.com.
No doubt you’ve heard the term “corrosive” used with respect to ammunition. But what exactly is “corrosive ammunition” (and how does it different from non-corrosive ammo)? What is the chemistry that leads to corrosion, and what cleaning procedures should you follow if you shoot corrosive ammunition? Brownells has come up with answers to these and other questions in a helpful TECH TIP video about corrosive ammo.
In this informative video, Brownells gun tech Steve Ostrem explains the primer-related chemistry that makes some ammo corrosive. The video then reviews suggested cleaning procedures you should follow after you have fired corrosive ammo through any firearms.
What Is “Corrosive” Ammunition?
What makes ammo “corrosive”? Generally speaking, primers are the problem. When corrosive ammunition is fired, the ignited primers leave a residue of corrosive salts. Typically these primers contain potassium chlorate, or sodium petrochlorate which, when burned, change into potassium chloride or sodium chloride. Sodium chloride is also known as common table salt.
Potassium chloride and sodium chloride are both very hygroscopic (i.e. they attract water). Because of that, these alkalis are rust generators. When exposed to the hydrogen and oxygen in the air (and moisture) potassium chloride and sodium chloride can form an acid that quickly causes metal rifle parts to rust and pit.
Given a choice, you may wish to avoid corrosive ammo altogether. However, for some types of fire-arms, particularly older military-style rifles, the most affordable ammunition may be corrosive. If you choose to use corrosive ammo, it is important to clean the gun thoroughly after use. After firing, you want to use an element that will neutralize the primer salts. Brownells suggests a water soak (see video above). Alternatively, Windex with ammonia can help neutralize the salts, but that doesn’t finish the job. After the salts have been neutralized and flushed away, basic anti-corrosion protectant (such as Eezox or other gun oil) should be applied to all metal parts.
To learn more about the proper procedures for cleaning rifles exposed to corrosive ammo, we suggest an article by Paul Markel on Ammoland.com. Markel, host of the popular Student of the Gun TV series, states that: “Windex (with ammonia) is the Corrosive Ammo shooter’s best friend. After you are done shooting your corrosive ammunition for the day, squirt the window cleaner liberally from the chamber down the barrel. Pull the bolt / bolt carrier / op rod if there is one and douse them as well. A couple of old cotton t-shirts will come in handy. A cotton barrel swab is a nice accessory but you can make do with patches. Some folks will rinse all of the ammonia and loosened corrosive salts off with hot water. Others prefer to wipe it all down and let the ammonia evaporate. Either way, once the corrosive salts have been tackled with the window cleaner, it is time for an all-purpose brush (old toothbrush) and some gun oil.” READ Full Article by Paul Markel.
Video Tip from EdLongrange. We welcome reader submissions.
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Denver Instrument, maker of the MXX and Timberline Series of precision balances, has created a helpful guide explaining how to get the best performance from a digital scale. Denver Instrument knows that, to achieve and maintain a very high level of accuracy with digital scales, they must be calibrated regularly, leveled properly, and kept away from sources of interference. Unfortunately, some reloaders treat their electronic scales as if the machines were toasters — something to place on a tabletop, plug into an outlet, then “set and forget.” There’s a better way to set up your scale and keep it functioning optimally. Here are ten guidelines provided by Denver Instrument. Follow these “Ten Commandments” and you’ll benefit:
ONE: Thou shalt choose the best resting spot. The performance of your balance depends greatly on the surrounding environment. Choose a location away from the main traffic flow of the room, especially doors. Also be aware of heating and cooling vents as these produce air movement. You can adjust the environmental settings on your balance to provide the best performance in the chosen location. Balances must be placed away from magnets as they affect the weigh cell performance.
TWO: Thou shalt avoid vibrations. Vibrations can come from large machinery in production environments and from fume hoods in laboratories. An alternative to fume hoods are Power Safety Workstations which are designed specifically for use with a balance.
THREE: Thou shalt watch temperature changes. On an analytical balance a one degree temperature change can cause a 1 digit (0.0001g) drift. Although Denver balances have temperature correction built-in, it is still important to calibrate your balance when the temperature changes significantly. Choosing to place your balance in a temperature controlled room, away from sunlight, and calibrating often helps minimize the effects of temperature.
FOUR: Thou shalt calibrate often. Upon installation and each time the balance is moved you should calibrate your balance. For example moving an analytical balance to a location that is only 13 feet higher changes the weight reading from 200.0000 g to 199.9997 g; which means the result is 0.0003 g lighter than the actual mass.
FIVE: Remember to check the level. The instrument should be leveled upon installation with all feet (two front feet for round pan units, four feet for square pan units) touching the countertop. If the level changes, the balance should be re-leveled and recalibrated. As an example, a 200g sample would weigh 0.0025 g less when tilted at an angle of 0.3°.
SIX: Honor thy weights. Keep in mind that weights are only as reliable as their quality and certification. Remember, a 1 g does not weigh precisely 1.00000 grams. Weights should be recertified annually. Denver Instrument offers recertification services on all weights 1 mg to 5 kg. Check to make sure you have selected the proper weight class for your balance. The weight tolerance should be better than balance readability. Always use tweezers or gloves when handling weights as smudges and indentations change the value of the weight. Keep weights in cases so they don’t get scratched or dusty.
SEVEN: Thou shalt always use a small container and weigh in the center of the pan. Especially when using an analytical balance, the effects of air buoyancy increase as the sample container size increases. Using a small sample container will minimize the effects. Items placed on the pan provide a downward force. Placing them directly in the center of the pan keeps corner loading errors at a minimum.
EIGHT: Thou shalt not unplug. To perform within published speci-fications, balances must have power applied for 30 minutes to 48 hours depending on the resolution of the balance. Denver balances have a standby mode which turn the display to standby but keep power cycling through the electronics.
NINE: Thou shalt not ignore static. Static is one of the most common weighing “noises”. It can cause reading to appear too high, too low or just be unstable. Denver balances include grounding methods to reduce the effects of static. However sometimes extra supplies are needed. Consider anti-static weigh dishes, anti-static brushes or low tech ways to increase the humidity of the chamber like placing damp cotton balls or glass wool in a small vial in the corner of the analytical draft shield.
TEN: Thou shalt clean often. Dirty weigh pans and powder in weighing chamber can contribute to static issues and lead to a wide variety of problems. Denver weigh pans are made from stainless steel and can be cleaned using a variety of household and laboratory chemicals. A small paint brush can be used to get power away from the edges of the draft shield for easy clean up.
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The ANSI / SAAMI group, short for “American National Standard Institute” and “Sporting Arms and Ammunition Manufacturers’ Institute”, have made available some time back the voluntary industry performance standards for pressure and velocity of centerfire rifle sporting ammunition for the use of commercial manufacturers. [These standards for] individual cartridges [include] the velocity on the basis of the nominal mean velocity from each, the maximum average pressure (MAP) for each, and cartridge and chamber drawings with dimensions included. The cartridge drawings can be seen by searching the internet and using the phrase ‘308 SAAMI’ will get you the .308 Winchester in PDF form. What I really wanted to discuss today was the differences between the two accepted methods of obtaining pressure listings. The Pounds per Square Inch (PSI) and the older Copper Units of Pressure (CUP) version can both be found in the PDF pamphlet.
CUP Pressure Measurement
The CUP system uses a copper crush cylinder which is compressed by a piston fitted to a piston hole into the chamber of the test barrel. Pressure generated by the burning propellant causes the piston to move and compress the copper cylinder. This will give it a specific measurable size that can be compared to a set standard. At right is a photo of a case that was used in this method and you can see the ring left by the piston hole.
PSI Pressure Measurement
What the book lists as the preferred method is the PSI (pounds per square inch or, more accurately, pound-force per square inch) version using a piezoelectric transducer system with the transducer flush mounted in the chamber of the test barrel. Pressure developed by the burning propellant pushes on the transducer through the case wall causing it to deflect and make a measurable electric charge.
Q: Is there a standardized correlation or mathematical conversion ratio between CUP and PSI values?
Mahin: As far as I can tell (and anyone else can tell me) … there is no [standard conversion ratio or] correlation between them. An example of this is the .223 Remington cartridge that lists a MAP of 52,000 CUP / 55,000 PSI but a .308 Winchester lists a 52,000 CUP / 62,000 PSI and a 30-30 lists a 38,000 CUP / 42,000 PSI. It leaves me scratching my head also but it is what it is. The two different methods will show up in listed powder data[.]
So the question on most of your minds is what does my favorite pet load give for pressure? The truth is the only way to know for sure is to get the specialized equipment and test your own components but this is going to be way out of reach for the average shooter, myself included. The reality is that as long as you are using printed data and working up from a safe start load within it, you should be under the listed MAP and have no reason for concern. Being specific in your components and going to the load data representing the bullet from a specific cartridge will help get you safe accuracy. [With a .308 Winchester] if you are to use the 1% rule and work up [from a starting load] in 0.4 grain increments, you should be able to find an accuracy load that will suit your needs without seeing pressure signs doing it. This is a key to component longevity and is the same thing we advise [via our customer service lines] every day. Till next time, be safe and enjoy your shooting.
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Derek Rodgers is a member of the Team Sinclair F-TR squad. This talented group of shooters hasn’t lost a team match in years. What’s the secret of Team Sinclair’s success? Well there is not one single factor. These guys have very accurate rifles, work hard on load development, and practice in all conditions. In this interview, Derek Rodgers talks about long range competition, reviewing the hardware (and skill set) it takes to win. He offers some great tips on developing loads. You’ll find a longer version of this interview on the Sinclair Int’l website. CLICK HERE to Read Full Interview.
Derek Rodgers BIOGRAPHY
Derek Rodgers (Albuquerque, NM), is the only shooter to have won BOTH the F-Open and F-TR National Championships. Derek shot his first NRA sanctioned-match in 2007, and just three years later Derek won the 2010 F-Open Nationals. He also won the 2013 F-TR Nationals, making him the only person to win both divisions. He has won other major F-TR matches, including the 2013 Sinclair East Coast Nationals and the 2015 Berger SW Nationals. Derek holds the current 1000-yard, 20-shot, National F-TR Record (200-12X). Derek enjoys spending his time outdoors with his wife and two daughters, ages 12 and 7. He is blessed by his faith and supported by his family. Derek’s goal is to pass on what he has learned to the next generation.
Q: What is your favorite reloading product?
I really like my BenchSource Case Annealer. There is something about watching fire that I find relaxing. I can watch those shells go around the wheel for hours.
Q: What’s your preferred front rest or bipod?
I’m currently using a Duplin bipod. At 17.2 ounces it allows me a solid platform to shoot from and the extra wiggle room to make weight with a heavy barrel and Nightforce NXS scope. Also, I can’t do without my board under the bipod. We shoot off sand at my local range and in most cases the feet will tend to dig holes if not supported. The board is necessary gear for me.
Q: What rear bag do you use?
I have an Edgewood bag that I’ve used for years. Recently, I got a SEB Bigfoot and like how it supports the gun and stays put under recoil.
Q: Explain your load development process. What’s your methodology?
I have two log books that have many combinations that work with 308s. I have tried to keep detailed notes in these books. Now I am reaping the rewards, as I can go back to a particular twist and barrel length and find something very close. I usually start with 3-shot groups and check the chamber behavior. If something looks promising I will go back to the range and load up 6-shot groups. If those shoot well, I take it to a match to verify it in a 20-shot string. If it passes that test it is either good to go or I table it and try another. I tend to pick mild loads that the cartridge shoots well — consistently.
Q: What piece of shooting gear helps your load development?
I use a MagnetoSpeed Chronograph to record velocities. Then I can slow down or speed up my loads to reach an accuracy node. It is amazing that most barrels will shoot very accurately when fired at certain known velocity nodes.
Q: What do you carry in your range bag on Match days?
Multi-piece Brownells tool set, RX Glasses, Sunglasses, Range Rod, Towel, Empty Chamber Indicators, Jacket, Sunscreen, Foam Ear Protection, Ear Muffs, Data Book, Plot Sheets, Pen, Clip Board, iPod with ballistic data, and chewing gum.
Q: How did you get started shooting?
I was raised in New Mexico where outdoor activities are abundant. Once my father introduced me to a Crossman pellet gun, all I wanted to do was shoot and refine my skills. Shooting evolved into hunting and then into perfecting my skills in off-season matches. Shooting local F-Class matches made me better as a marksman. Now I feel like I am competitive with anyone. However, I will never forget that my roots started with hunting and still cherish the opportunity to hunt…
Q: What do you find most challenging? How do you learn from mistakes?
What I find most challenging about precision shooting sports is how great shooters are able to reflect on what was learned — both positively and negatively. It is important to slow down and perform this step. Stopping to reflect and learn from mistakes I’ve made on the firing line is challenging. Not many people enjoy accurately critiquing themselves. Also the wind usually blows here in New Mexico and choosing the right time to shoot and to stop is important. It’s often tempting to try to finish out a string of fire. But sometimes challenging yourself to quit and wait out some wind will pay off[.]
Q: What advice do you have for selecting a gunsmith?
The best recommendation I can give is for a person to get to know a gunsmith. If you can find a local gunsmith that is available — even better! If you run into a snag along the way, it is so nice to be able to work it out without sending things back and forth. Be honest, realistic with your expectations and tell the gunsmith what you want. If he only wants to do things his way, or takes extra or excessive time in meeting the goals, you may want to consider someone else.
Q: Who would you recommend for stock work on your rifle?
Alex Sitman from Master Class Stocks and Doan Trevor can build or fix most anything.
Q: What do you do to mentally prepare before a shooting competition?
I relax and try to remember I do this for fun. I anticipate what game plan I want to go to the line with. I also try to take small snapshots of the conditions. I do not like getting overloaded with staring down a spotting scope for long periods of time. I try not to get overwhelmed with the match and just shoot my game. My approach is “One shot at a time — good or bad”. I will usually tell my scorer what I’m going to do so he or she is ready as well.
Q: What advice would you give to novice competitors?
Partner up with an experienced shooter that is ranked nationally. Mentoring under a veteran shooter would be the best way to help save time learning instead of experimenting. Chances are an experienced shooter has already tried what you are considering. As a new shooter, do not get sucked into reading all of the opinionated blogs on the internet. Stick to good information. AccurateShooter.com | 6mmBR.com is a great resource with a wealth of information from knowledgeable writers. That site has articles that are based from facts and/or industry news and information.
Q: What is something you would NOT recommend before a shoot?
I do not recommend coming unprepared. If you are late, scrambling around, or do not have your gear in order, you will not perform at your best.
Q: How many rounds do you shoot in a year and how often do you practice?
I shoot 3000+ rounds a year. I try to shoot 1 x a week if I can get away in the evening or on the weekend. If I am close to finding a load I may try to get out more until I exhaust that load as an option. So there may be occasions that I will try to shoot three times a week. Fortunately, the winters are mild in New Mexico and it allows me to shoot year round. I actually shoot more when it is colder. The summer sun here can create mirage that makes it nearly impossible to learn anything.
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Jonathan Ocab, a High Power shooter from California, had gunsmith Doan Trevor install a Sako-style extractor in the Rem 700 bolt in Ocab’s 6mmBR Eliseo R5 tubegun. Jonathan produced an excellent video showing how the Sako extractor improves the ejection of the short, fat 6mmBR cartridges in his rifle. Jonathan’s video demonstrates 6mmBR case ejection with an unmodified Rem 700 factory bolt versus a factory bolt fitted with a Sako-style extractor.
Johnathan explains: “Note how even when slowly operating the bolt, the bolt with the Sako extractor easily ‘kicks’ out the brass on ejection with minimal chance of operator error resulting in a failure to extract. While the unmodified bolt has issues ejecting brass on slow operation, it will eject if the operator pulls the bolt back quickly (fast and with some force).
While a Sako-style extractor isn’t an absolute necessity, this video shows the definite improvement this modification provides. For short cartridges like the 6mmBR, this is very useful. This modification is highly recommended for competition shooters, especially High Power competitors who seek improved function in rapid-fire stages. This modification is fairly inexpensive and any competent gunsmith should be able to perform the work (usually under $100 with parts and labor).”
EDITOR’s NOTE: In his video, Jonathan deliberately worked the unmodified Remington bolt slowly to show how the standard Rem extractor can struggle with short fat cases like the 6mmBR. In fact, when you work a standard, unmodified bolt more quickly, the extraction can be much more positive. Cycling the bolt with more “snap” provides more energy to eject the cases. We have run an R5 Tubegun chambered in 6mmBR with an unmodified Rem 700 bolt (no SAKO extractor), and the extraction was reliable, provided the bolt was worked quickly.
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Larry Racine is a respected gunsmith based in New Hampshire. He is also a two-time member of the U.S. Palma Team, and a five-time New Hampshire State High Power rifle champion. Larry, who runs LPR Gunsmithing, has developed a brilliantly simple means of switching rifle barrels with an ordinary spanner or open-end wrench. With this set-up you can switch barrels in the field in seconds without the need for a barrel vise.
For most barrels, Larry mills a hex with six flats on the end of the barrel. This allows a shooter to change barrels quickly at home or on the line with a simple box-head wrench or a socket wrench. Larry says: “You don’t even have to take the barreled action out of the gun. Just set the buttstock on the ground, between your feet, put a wrench on it, hit it with the palm of your hand — and off comes the barrel.” For barrels fitted with a muzzle brake, Larry has a slightly different system. He mills two flats behind the brake so you can use an open-end wrench to do the job.
With either a hex on the end, or two flats for a brake-equipped rifle, the system works with any medium- to heavy-contour barrel with a muzzle-diameter of at least 0.700″. This will even work for high-power rigs using clamp-on sights or bloop tubes. Larry explains: “A lot of us here in New England use clamp-on front sights. The barrel will be turned to 0.750 for the sight, with the hex on the end. A bloop tube can go right over the end, no problem.”
Larry has used this system over the past few years to win a number of matches. In one 600-yard 3 by 20 prone match, Larry used three different barrels, with three different chamberings, on the same Savage rifle. Larry changed the barrels on the line.
Larry was able to do this because the system has little to no loss of zero from one installation of a given barrel to the next installation of that barrel. This lets the shooter start the match with confidence that the first sighter will be on paper. Larry reports that the simple system works great: “To date we have used this system on Savage, Remington, Winchester, RPA, and Nesika actions.”
Racine’s system is very affordable. If Larry does the chamber work on your barrel he charges $45.00 extra to mill a hex or two flats on your barrel. If you only want the hex or flats done, Larry charges $55.00. For more info, visit LPRGunsmith.com or call Larry at (603) 357-0055.
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Bryan Litz has produced an informative new video on the subject of bullet stability. The video explains how stability is related to spin rate (or RPM), and how RPM, in turn, is determined by barrel twist rate and velocity. For long-range shooting, it is important that a barrel have a fast-enough twist rate to stabilize the bullet over its entire trajectory.
Detailed Bullet Stability Article
To complement the above video, Bryan has authored a detailed article that explains the key concepts involved in bullet stabilization. Bryan explains: “Bullet stability can be quantified by the gyroscopic stability factor, SG. A bullet that is fired with inadequate spin will have an SG less than 1.0 and will tumble right out of the barrel. If you spin the bullet fast enough to achieve an SG of 1.5 or higher, it will fly point forward with accuracy and minimal drag.”
There is a “gray zone” of marginal stability. Bryan notes: “Bullets flying with SGs between 1.0 and 1.5 are marginally stabilized and will fly with some amount of pitching and yawing. This induces extra drag, and reduces the bullets’ effective BC. Bullets in this marginal stability condition can fly with good accuracy and precision, even though the BC is reduced. For short range applications, marginal stability isn’t really an issue. However, shooters who are interested in maximizing performance at long range will need to select a twist rate that will fully stabilize the bullet, and produce an SG of 1.5 or higher.”
Berger Twist-Rate Stability Calculator
On the updated Berger Bullets website you’ll find a handy Twist-Rate Stability Calculator that predicts your gyroscopic stability factor (SG) based on mulitiple variables: velocity, bullet length, bullet weight, barrel twist rate, ambient temperature, and altitude. This very cool tool tells you if your chosen bullet will really stabilize in your barrel.
LIVE DEMO BELOW — Just enter values in the data boxes and click “Calculate SG”.
For a prone shooter, particularly on dusty, dirty or sandy ground, muzzle blast is a major bummer. Muzzle blast can be very disturbing — not just for the trigger-puller but for persons on either side of the gun as well. Some muzzle brakes send a huge shockwave back towards the shooter, and others send blast towards the ground, kicking dirt and debris into the prone shooter’s face. If there was a way to illustrate those factors — shockwave and debris — that might help shooters select one brake design over another.
Cal Zant at PrecisionRifleBlog.com applied a unique blend of creativity and resourcefulness to try to answer that question for 20+ muzzle brakes. Using high-speed photography and household products, he captured the blast pattern of 20+ different brake designs for easy side-by-side comparison. Can you figure out how Cal managed to show muzzle brake blasts so clearly? His “hi-viz” solution, revealed in the article, is very clever. See the eye-opening results for 20+ brakes, with illustrative photos, by visiting the Precision Rifle Blog Muzzle Brake Ground Signature Test Page.
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German Salazar has written a very thorough guide to measuring nearly all the critical dimensions of cartridge brass. In his Measuring the Case article, on his Rifleman’s Journal website, German reviews the tools and techniques required to measure everything from case overall length to case neck concentricity. Step-by-step, German shows how to measure: Case Length, Case Body length (below neck), Neck Diameter, Headspace, Base Diameter, Neck Thickness, and Case Neck Concentricity.
If you are an “advanced reloader” or want to be, you should read German’s article. Not only does German explain the most common measuring procedures, he highlights some alternative methods you might not have tried yet. The article also links to related discussions of more complex measurement tasts, such as determining case body wall thickness variation.
Even if you’re not a competitive shooter, measuring your brass can provide important safety benefits. As German explains in the conclusion of his article: “There are obviously a lot of measurements that can be taken on the cartridge case and in some cases, more than one way to take them. However, the first two that any new reloader must learn are case length and neck clearance, these two are safety concerns and if overlooked can results in serious damage to the rifle and injury to you.”
We are re-publishing this article at the request of Forum members who told us the information proved very valuable. If you haven’t read this Safety Tip before, take a moment to learn how you can inspect your fired brass to determine if there may be a potential for case separation. A case separation can be dangerous, potentially causing serious injury.
On his Riflemans’ Journal blog, German Salazar wrote an excellent article about cartridge Case-Head Separation. We strongly recommend that you read this article. German examines the causes of this serious problem and he explains the ways you can inspect your brass to minimize the risk of a case-head separation. As cases get fired multiple times and then resized during reloading, the cases can stretch. Typically, there is a point in the lower section of the case where the case-walls thin out. This is your “danger zone” and you need to watch for tell-tale signs of weakening.
The photo at the top of this article shows a case sectioned so that you can see where the case wall becomes thinner near the web. German scribed a little arrow into the soot inside the case pointing to the thinned area. This case hadn’t split yet, but it most likely would do so after one or two more firings.
One great tip offered by German Salazar involves using a bent paper clip to detect potential case wall problems. Slide the paper clip inside your case to check for thin spots. German explains: “This simple little tool (bent paper clip) will let you check the inside of cases before you reload them. The thin spot will be immediately apparent as you run the clip up the inside of the case. If you’re seeing a shiny line on the outside and the clip is really hitting a thin spot inside, it’s time to retire the case. If you do this every time you reload, on at least 15% of your cases, you’ll develop a good feel for what the thin spot feels like and how it gets worse as the case is reloaded more times. And if you’re loading the night before a match and feel pressured for time — don’t skip this step!”
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In this detailed 22-minute video, John McQuay of 8541 Tactical shows how to input firearm specs, MV, and BC into a Kestrel 4500 NV (Applied Ballistics model). This handy unit combines a Kestrel Weather meter with a full-fledged ballistics computer.
Step-by-step the video shows how to set up all the important variables. The video shows how to input Muzzle Velocity, Bullet BC (G1 or G7), Zero Distance and the other key ballistics variables. In addition, the video explains how to input gun-specific data such as bore height, barrel twist rate, and barrel rifle twist direction (right-hand vs. left-hand). (Twist direction comes into play in long range spin drift calculations).
If you own a Kestrel 4500 NV (Applied Ballistics), we think you’ll find this video helpful — particularly when it comes to setting up some of the lesser-known data items. The video also offers tips on navigating through the menus most efficiently.
Each Wednesday, the U.S. Army Marksmanship Unit publishes a reloading “how-to” article on the USAMU Facebook page. This USAMU “Handloading Hump Day” article, the second in a series on improving concentricity, has many useful tips. If you use standard (non-micrometer) seating dies when loading some cartridge types, this article is worth reading. And visit the USAMU Facebook page next Wednesday for the next installment.
Once again, it’s time for USAMU’s “Handloading Hump-Day!” Last week, we addressed achieving very good loaded-cartridge concentricity (AKA “TIR”, or Total Indicator Runout) using standard, “hunting grade” reloading dies.
We explained how to set up the Full-Length Size die to float slightly when correctly adjusted for desired case headspace. We also cited a study in which this method loaded ammunition straighter than a set of [higher grade] match dies from the same maker. [One of the keys to reducing TIR with both sets of dies was using a rubber O-ring below the locking ring to allow the die to float slightly. READ Full-Length Sizing Die TIP HERE.]
Now, we’ll set up a standard seating die to minimize TIR — the other half of the two-die equation. As before, we’ll use a single-stage press since most new handloaders will have one. A high-quality runout gauge is essential for obtaining consistent, accurate results.
Having sized, primed and charged our brass, the next step is bullet seating. Many approaches are possible; one that works well follows. When setting up a standard seating die, insert a sized, trimmed case into the shell-holder and fully raise the press ram. Next, back the seating stem out and screw the die down until the internal crimping shoulder touches the case mouth.
Back the die out one-quarter turn from this setting to prevent cartridge crimping. Next, lower the press ram and remove the case. Place a piece of flat steel on the shellholder and carefully raise the ram. Place tension on the die bottom with the flat steel on the shellholder. This helps center the die in the press threads. Check this by gently moving the die until it is well-centered. Keeping light tension on the die via the press ram, secure the die lock ring.
If one were using a micrometer-type seating die, the next step would be simple: run a charged case with bullet on top into the die and screw the seating stem down to obtain correct cartridge OAL.
However, with standard dies, an additional step can be helpful. When the die has a loosely-threaded seating stem, set the correct seating depth but don’t tighten the stem’s lock nut. Leave a loaded cartridge fully raised into the die to center the seating stem. Then, secure the stem’s lock nut. Next, load sample cartridges and check them to verify good concentricity.
One can also experiment with variations such as letting the seating stem float slightly in the die to self-center, while keeping correct OAL. The runout gauge will show any effects of changes upon concentricity. However, the first method has produced excellent, practical results as evidenced by the experiment cited previously. These results (TIR Study 2) will reproduced below for the reader’s convenience.
TIR Study 2: Standard vs. Match Seating Dies
50 rds of .308 Match Ammo loaded using carefully-adjusted standard dies, vs. 50 using expensive “Match” dies from the same maker.
Standard dies, TIR:
0.000” — 0.001” = 52%;
0.001”– 0.002” = 40%;
0.002”– 0.003” = 8%. None greater than 0.003”.
AccurateShooter Comment: This shows that, with careful adjustment, the cheaper, standard dies achieved results that were as good (or better) than the more expensive “Match” Dies.
These tips are intended to help shooters obtain the best results from inexpensive, standard loading dies. Especially when using cases previously fired in a concentric chamber, as was done above, top-quality match dies and brass can easily yield ammo with virtually *no* runout, given careful handloading.
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Here’s a great tip from Forum member Greg C. (aka “Rem40X”). Greg has created a trajectory table with windage and elevation data for various distances and wind speeds. Greg prints out a compact version of his drop chart to place on his rifle. While many shooters tape a ‘come-up’ table on their buttstock, Greg has a better solution. He tapes the trajectory table to the outside of his front flip-up scope cover. This way, when he flips up the cover, his data is displayed for easy viewing right in front.
With your ‘come-up’ table on the flip-up cover you can check your windage and elevation easily without having to move up off the rifle and roll the gun over to look at the side of the stock. Greg tells us: “Placing my trajectory table on the front scope cover has worked well for me for a couple of years and thought I’d share. It’s in plain view and not under my armpit. And the table is far enough away that my aging eyes can read it easily. To apply, just use clear tape on the front objective cover.”
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We’ve all seen them — you know those guys who don’t follow range rules, or who handle firearms in a careless manner. Sometimes bad range etiquette is simply annoying. Other times poor gun-handling practices can be downright dangerous. The NRA Blog has published a useful article about range safety and “range etiquette”. While these tips were formulated with indoor ranges in mind, most of the points apply equally well to outdoor ranges. You may want to print out this article to provide to novice shooters at your local range or club.
8 Tips for Gun Range Etiquette
Story by Kyle Jillson for NRABlog
Here are eight tips on range etiquette to keep yourself and others safe while enjoying your day out [at the range]. Special thanks to NRA Headquarters Range General Manager Michael Johns who assisted with this article.
1. Follow the Three Fundamental Rules for Safe Gun Handling
ALWAYS keep the gun pointed in a safe direction.
ALWAYS keep your finger off the trigger until ready to shoot.
ALWAYS keep the gun unloaded until ready to use.
2. Bring Safety Gear (Eye and Ear Protection)
Eye and Ear protection are MANDATORY for proper safety and health, no matter if “required” by range rules or not. It is the shooter’s responsibility to ensure proper protection is secured and used prior to entering/using any range. Hearing loss can be instantaneous and permanent in some cases. Eyesight can be ruined in an instant with a catastrophic firearm failure.
3. Carry a Gun Bag or Case
Common courtesy and general good behavior dictates that you bring all firearms to a range unloaded and cased and/or covered. No range staff appreciates a stranger walking into a range with a “naked” firearm whose loaded/unloaded condition is not known. You can buy a long gun sock or pistol case for less than $10.
4. Know Your Range’s Rules
Review and understand any and all “range specific” rules/requirements/expectations set forth by your range. What’s the range’s maximum rate of fire? Are you allowed to collect your brass? Are you required to take a test before you can shoot? Don’t be afraid to ask the staff questions or tell them it’s your first time. They’re there to help.
5. Follow ALL Range Officer instructions
ROs are the first and final authority on any range and their decisions are generally final. Arguing/debating with a Range Officer is both in poor taste and may just get you thrown out depending on circumstances.
6. Don’t Bother Others or Touch Their Guns
Respect other shooters’ privacy unless a safety issue arises. Do NOT engage other shooters to correct a perceived safety violation unless absolutely necessary – inform the RO instead. Shooters have the right and responsibility to call for a cease fire should a SERIOUS safety event occur. Handling/touching another shooter’s firearm without their permission is a major breech of protocol. Offering unsolicited “training” or other instructional suggestions to other shooters is also impolite.
7. Know What To Do During a Cease Fire
IMMEDIATELY set down your firearm, pointed downrange, and STEP AWAY from the shooting booth (or bench). The Range Officer(s) on duty will give instructions from that point and/or secure all firearms prior to going downrange if needed. ROs do not want shooters trying to “secure/unload” their firearms in a cease fire situation, possibly in a stressful event; they want the shooters separated from their guns instantly so that they can then control the situation as they see fit.
8. Clean Up After Yourself
Remember to take down your old targets, police your shooting booth, throw away your trash, and return any equipment/chairs, etc. Other people use the range too; no one wants to walk up to a dirty lane.
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Hunters and tactical shooters need scopes with good low-light performance. For a scope to perform well at dawn and dusk, it needs good light transmission, plus a reasonably large exit pupil to make maximum use of your eye’s light processing ability. And generally speaking, the bigger the front objective, the better the low-light performance, other factors being equal. Given these basic principles, how can we quickly evaluate the low-light performance of different makes and models of scopes?
Here’s the answer: ScopeCalc.com offers a FREE web-based Low-Light Performance Calculator that lets you compare the light gain, perceived brightness, and overall low-light performance of various optics. Using this scope comparison tool is pretty easy — just input the magnification, objective diameter, exit pupil size, and light transmission ratio. If the scope’s manufacturer doesn’t publish an exit pupil size, then divide the objective diameter in millimeters by the magnification level. For example a 20-power scope with a 40mm objective should have a 2mm exit pupil. For most premium scopes, light transmission rates are typically 90% or better (averaged across the visible spectrum). However, not many manufacturers publish this data, so you may have to dig a little.
ScopeCalc.com’s calculator can be used for a single scope, a pair of scopes, or multiple scopes. Once you’ve typed in the needed data, click “Calculate” and the program will produce comparison charts showing Light Gain, Perceived Brightness, and Low-Light Performance. Though the program is easy to use, and quickly generates comparative data, assessing scope brightness, as perceived by the human eye, is not a simple matter. You’ll want to read the annotations that appear below the generated charts. For example, ScopeCalc’s creators explain: “Perceived brightness is calculated as the cube root of the light gain, which is the basis for modern computer color space brightness scaling.”
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Do you have some old, tired brass that needs a thorough cleaning — inside and out? Consider using an ultrasonic cleaning machine. When used with the proper solution, a good ultrasonic cleaning machine can quickly remove remove dust, carbon, oil, and powder residue from your cartridge brass. The ultrasonic process will clean the inside of the cases, and even the primer pockets. Tumbling works well too, but for really dirty brass, ultrasonic cleaning may be a wise choice.
Our friend Gavin Gear recently put an RCBS Ultrasonic cleaning machine through its paces using RCBS Ultrasonic Case Cleaning Solution (RCBS #87058). To provide a real challenge, Gavin used some very dull and greasy milsurp brass: “I bought a huge lot of military once-fired 7.52x51mm brass (fired in a machine gun) that I’ve been slowly prepping for my DPMS LR-308B AR-10 style rifle. Some of this brass was fully prepped (sized/de-primed, trimmed, case mouths chamfered, primer pockets reamed) but it was gunked up with lube and looking dingy.”
UltimateReloader.com Case Cleaning Video (7.5 minutes):
Gavin describes the cleaning exercise step-by-step on UltimateReloader.com. Read Gavin’s Cartridge Cleaning Article to learn how he mixed the solution, activated the heater, and cycled the machine for 30 minutes. As you can see in the video above, the results were impressive. If you have never cleaned brass with ultrasound before, you should definitely watch Gavin’s 7.5-minute video — it provides many useful tips and shows the cleaning operation in progress from start to finish.
The RCBS ultrasonic cleaning machine features a large 3-liter capacity, 60 watt transducer, and 100 watt ceramic heater. The RCBS ultrasonic machine can be found under $140.00, and this unit qualifies for RCBS Rebates ($10 off $50 purchase or $50 off $300.00 purchase). RCBS also sells 32 oz. bottles of cleaning concentrate that will make up to 10 gallons of Ultrasonic Solution.
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by Tony Chow
In recent years, the use of electronic trainer systems has revolutionized training in all disciplines of position shooting. By capturing (and illustrating) key performance variables like the steadiness of a shooter’s hold, accuracy of aiming, and the timeliness of trigger release, these devices can offer tremendous insights into the strengths and weakness of a shooter’s position and technique, making high-level marksmanship training less voodoo and more of a science.
Until now, electronic trainers all suffered from one critical limitation: the inability to be used outdoors in live fire training. Now, however, SCATT has introduced the next-generation MX-02 electronic trainer, a product that can finally support outdoor live firing in broad daylight, as well as dry firing indoors. In addition, the MX-02 is the first electronic trainer to support centerfire rifles. It goes without saying that, when we at AccurateShooter.com were offered an MX-02 test unit to review, we jumped at the opportunity.
How the SCATT MX-02 Works
The SCATT sensor mounted on the end of the barrel has a digital camera that “sees” the black bullseye in the target, even in broad daylight outdoors. Using the bullseye as a reference, the SCATT software tracks the movement of the muzzle relative to the center of the target. The unit can plot these movements as a continuous trace, which appears on a monitor as a squiggly, colored line. Data points from the trace are also available in a tabular spreadsheet format. This allows the shooter to “crunch the numbers”, revealing strengths and weaknesses in his gun-handling and aiming technique.
In our testing, we confirmed that, like SCATT’s earlier indoor-only WS-01, the MX-02 offers excellent support for indoor dry-fire training, which will continue to be the primary means through which position shooters sharpen their fundamental skills. Since the new SCATT uses the same familiar Windows software for data capture and analysis as its predecessors, shooters and coaches upgrading to MX-02 will have no learning curve to overcome, and newcomers to the SCATT platform can tap into the wealth of institutional knowledge accumulated over the years by the shooting community on how to interpret shot data.
It’s in the support for outdoor live firing, however, that SCATT MX-02 distinguishes itself from its predecessors and the competition. Shot trace data captured by MX-02 during live firing turned out to be every bit as valuable (and revealing) as we had hoped. The ability to correlate SCATT tracing with real shots on target gave us a better understanding of the shooting process, and helped the reviewer, already a high-level smallbore prone shooter, uncover a significant problem in his shooting. SCATT MX-02’s outdoor capability is therefore an invaluable feature, particularly for experienced shooters aspiring to world-class performance.
In summary, SCATT MX-02 is an outstanding product that delivers on its promises. We heartily recommend it, both for first-time users of electronic training aids, and also for those shooters who may wish to upgrade their current electronic training system. The MSRP for SCATT MX-02 is $1,799, $500 more than its predecessor, the SCATT WS-01, which is still available. In my view, the $500 premium for the MX-02 is justified by the MX-02’s enhanced capabilities, making it a better long-term investment.
Our complete, 3600-word MX-02 review of the SCATT MX-02 can be accessed through the link below. This full review contains many more photos plus detailed field test results. For the time being, the review only covers our experience with the product in smallbore shooting. An upcoming addendum to the review will include test results from centerfire shooting. Those attending SHOT Show in Las Vegas next week can examine SCATT MX-02 in person. SCATT will have the MX-02 on display at Booth 111.
Many visitors to the site ask us, “I’ve got a .223 and .308. What will a 6mmBR Norma (6BR) give me that I’m not getting already?” Well first you will probably average consistently smaller groups than your current .223 or .308 rifle (assuming the 6BR has a quality barrel and trigger). A good .308 Winchester can be superbly accurate, no question about that, but the lesser recoil of the 6BR works in the shooter’s favor over a long string of fire. Even with a Rem 700 or Savage action factory action, a 6BR with a benchrest stock, premium barrel, and a high-quality chambering job should deliver 5-shot groups in the high twos to mid-threes, provided you do your job. We have one 6BR rifle that shoots Lapua factory-loaded 6BR ammunition in the low twos and high ones. That’s exceptional, we admit, but it still shows how the 6BR is an inherently accurate cartridge, even with factory loads.
Compared to a .223, the 6BR offers a much better selection of high-BC projectiles, and will deliver considerably more power on the target. Compared to the .308 shooting 168gr MatchKings, a 6BR shooting 105-107gr bullets offers better ballistics all the way out to 1000 yards. Plus, for most people, the 6BR is just easier to shoot than a .308. Recoil is less than half of the .308 cartridge. Both the .308 and 6BR chamberings offer good barrel life, but the 6BR uses 15-18 grains less powder, saving you money. On the other hand the .308 is the designated cartridge for F-TR and Palma shooting, so it may be a more versatile chambering for Long-Range competition. So which would we choose between the 6BR and the .308? Actually we think you should have both. The 6BR is my favorite cartridge out to 500 yards, and I like the .308 Win for F-TR. And… if you want to shoot at the World Fullbore Championships this week at Camp Perry there’s only one choice — a .308 Win.
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Every summer weekend, there are probably 400 or more club “fun matches” conducted around the country. One of the good things about these club shoots is that you don’t have to spend a fortune on equipment to have fun. But we’ve seen that many club shooters handicap themselves with a few common equipment oversights or lack of attention to detail while reloading. Here are SIX TIPS that can help you avoid these common mistakes, and build more accurate ammo for your club matches.
1. Align Front Rest and Rear Bags. We see many shooters whose rear bag is angled left or right relative to the bore axis. This can happen when you rush your set-up. But even if you set the gun up carefully, the rear bag can twist due to recoil or the way your arm contacts the bag. After every shot, make sure your rear bag is aligned properly (this is especially important for bag squeezers who may actually pull the bag out of alignment as they squeeze).
Forum member ArtB adds: “To align my front rest and rear bag with the target, I use an old golf club shaft. I run it from my front rest stop through a line that crosses over my speed screw and into the slot between the two ears. I stand behind that set-up and make sure I see a straight line pointing at the target. I also have a piece of tape that I’ve placed on the golf shaft that indicates how far the back end of the rear bag should be placed from the front rest stop. Don’t have an old golf shaft? Go to Home Depot and buy an inexpensive piece of wood dowel.”
2. Avoid Contact Interference. We see three common kinds of contact or mechanical interference that can really hurt accuracy. First, if your stock has front and/or rear sling swivels make sure these do NOT contact the front or rear bags at any point of the gun’s travel. When a sling swivel digs into the front bag that can cause a shot to pop high or low. To avoid this, reposition the rifle so the swivels don’t contact the bags or simply remove the swivels before your match. Second, watch out for the rear of the stock grip area. Make sure this is not resting on the bag as you fire and that it can’t come back to contact the bag during recoil. That lip or edge at the bottom of the grip can cause problems when it contacts the rear bag. Third, watch out for the stud or arm on the front rest that limits forward stock travel. With some rests this is high enough that it can actually contact the barrel. We encountered one shooter recently who was complaining about “vertical flyers” during his match. It turns out his barrel was actually hitting the front stop! With most front rests you can either lower the stop or twist the arm to the left or right so it won’t contact the barrel.
3. Weigh Your Charges — Every One. This may sound obvious, but many folks still rely on a powder measure. Yes we know that most short-range BR shooters throw their charges without weighing, but if you’re going to pre-load for a club match there is no reason NOT to weigh your charges. You may be surprised at how inconsistent your powder measure actually is. One of our testers was recently throwing H4198 charges from a Harrell’s measure for his 30BR. Each charge was then weighed twice with a Denver Instrument lab scale. Our tester found that thrown charges varied by up to 0.7 grains! And that’s with a premium measure.
4. Measure Your Loaded Ammo — After Bullet Seating. Even if you’ve checked your brass and bullets prior to assembling your ammo, we recommend that you weigh your loaded rounds and measure them from base of case to bullet ogive using a comparator. If you find a round that is “way off” in weight or more than .005″ off your intended base to ogive length, set it aside and use that round for a fouler. (Note: if the weight is off by more than 6 or 7 grains you may want to disassemble the round and check your powder charge.) With premium, pre-sorted bullets, we’ve found that we can keep 95% of loaded rounds within a range of .002″, measuring from base (of case) to ogive. Now, with some lots of bullets, you just can’t keep things within .002″, but you should still measure each loaded match round to ensure you don’t have some cases that are way too short or way too long.
5. Check Your Fasteners. Before a match you need to double-check your scope rings or iron sight mounts to ensure everything is tight. Likewise, you should check the tension on the screws/bolts that hold the action in place. Even with a low-recoiling rimfire rifle, action screws or scope rings can come loose during normal shooting.
6. Make a Checklist and Pack the Night Before. Ever drive 50 miles to a match then discover you have the wrong ammo or that you forgot your bolt? Well, mistakes like that happen to the best of us. You can avoid these oversights (and reduce stress at matches) by making a checklist of all the stuff you need. Organize your firearms, range kit, ammo box, and shooting accessories the night before the match. And, like a good Boy Scout, “be prepared”. Bring a jacket and hat if it might be cold. If you have windflags, bring them (even if you’re not sure the rules allow them). Bring spare batteries, and it’s wise to bring a spare rifle and ammo for it. If you have just one gun, a simple mechanical breakdown (such as a broken firing pin) can ruin your whole weekend.
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A Kestrel Wind Meter will record wind speed with its impeller wheel. However, to get the most accurate wind velocity reading, you need to have your Kestrel properly aligned with the wind direction. To find wind direction, first orient the Kestrel so that the impeller runs at minimal speed (or stops), and only then turn the BACK of the Kestrel into the wind direction. Do NOT simply rotate the Kestrel’s back panel looking for the highest wind speed reading — that’s not the correct method for finding wind direction. Rotate the side of the Kestrel into the wind first, aiming for minimal impeller movement. The correct procedure is explained below by the experts at Applied Ballistics.
How to Find the Wind Direction with a Kestrel Wind Meter
Here is the correct way to determine wind direction with a Kestrel wind meter when you have no environmental aids — no other tools than a Kestrel. (NOTE: To determine wind direction, a mounted Wind Vane is the most effective tool, but you can also look at flags, blowing grass, or even the lanyard on your Kestrel).
Step 1: Find the wind’s general direction.
Step 2: Rotate the Wind Meter 90 degrees, so that the wind is impacting the side (and not the back) of the wind meter, while still being able to see the impeller.
Step 3: Fine-tune the direction until the impeller drastically slows, or comes to a complete stop (a complete stop is preferred). If the impeller won’t come to a complete stop, find the direction which has the lowest impact on the impeller.
Step 4: Turn the BACK of the Kestrel towards the direction from which the wind is blowing. Then press the capture button, and record your wind speed.
Do NOT simply point the Kestrel’s back into the wind until you get the highest wind speed — that’s not the correct method.
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