This is an interesting technical article prepared by Action Target, a leading steel target manufacturer based in Provo, Utah. With technical data provided by the American Iron and Steel Institute in Washington D.C., this report is designed to cut through the recent hype and establish a basis of fact for accurate evaluation and comparison.
What Is Steel?
Steel is an alloy metal composed of iron and varying amounts of carbon and/or other elements such as chromium, nickel, tungsten, manganese, and so on. Steel with specific properties and characteristics is created by adjusting the overall chemical composition or by altering the various production processes such as rolling, finishing, and heat treatment. Because each of these factors can be modified, there is potentially no limit to the number of different steel recipes that can be created. Currently, there are over 3,000 cataloged grades or chemical compositions of steel available. Steel can utilize a wide variety of alloying elements and heat treatments to develop the most desirable combination of properties.
Editor’s Comment: This is not the only way to clean a rimfire barrel. There are other procedures. This is the method recommended by ELEY based on decades of experience with the top smallbore shooters in the world, including many Olympic Gold Medalists. Some shooters have been very successful cleaning less frequently, or using different types of solvents. The ELEY method is a good starting point.
Rimfire Barrel Cleaning
1. Clean the extension tube with a 12 gauge brush and felt or tissue moistened with solvent.
2. Smoothly insert a cleaning rod guide into the receiver.
3. Apply a dry felt to the cleaning rod adapter and push it through the barrel to the muzzle in one slow steady movement. As the felt is dry it may feel stiff.
Some people love tuners and others hate them. I use them on my rifles and I’ve had more than one person ask me why on earth I would put one of those things on my barrel. I’ve even had a national long range champion tell me to unscrew it and throw it into Lake Erie on my next trip to the pits at Camp Perry. However, there are other shooters that swear by them and have many match wins to back it up.
It’s an indisputable fact that tuners do have an effect on a rifle’s accuracy, however how much is somewhat open for debate. The large heavy target barrels that we use for benchrest or f-class may not be affected as much by a tuner as a lighter weight sporter type barrel. Each barrel that I’ve installed a tuner on not only showed improvement in accuracy but also displayed a wider load window. The increased accuracy is because of the ability to adjust the tuner to the load, however I believe the wider load window is due to the added weight of the tuner slowing down the barrel vibrations. These are both very important aspects of having a very accurate rifle.
While better accuracy and a wider load window are two areas of improvement, I believe the most important feature of a tuner is the ability to adjust the tune during the middle of a match. This is especially important during matches where you must load all your ammo earlier and cannot make adjustments to the load during the match. If you happen to miss the load, instead of having to deal with a gun that isn’t shooting you can make an adjustment to the tuner and hopefully improve the accuracy of the rifle.
While I’ve laid out several ways that a tuner can help, there are also a few ways that tuners can cause problems. They add weight so if you are shooting a discipline that has weight limits on the rifle, you may not be able to install a tuner and still make weight. Sometimes, a barrel just doesn’t show improvement with a tuner installed. These are few and far between, but it is something to consider. If you make an adjustment to the tuner in a match, you need to make sure you move it in the right direction. Adjusting a tuner in the wrong direction can cause very large groups. And finally, if they aren’t tightened properly, tuners can come loose during firing which will cause a lot of problems as well.
As you can see, tuners have both positive and negative aspects. In my personal experience, the positives far outweigh the negatives so I will continue to use them on all of my competitive rifles. If you’ve been thinking about installing a tuner, hopefully some of the information that I’ve presented will help you make an informed decision.
Share the post "Tech Tip: Pros and Cons of a Barrel Tuner"
Over the years, noted gunsmith and a Benchrest Hall-of-Fame inductee Thomas ‘Speedy’ Gonzalez has learned a few things about “tuning” rear sandbags for best performance. On his Facebook page, Speedy recently discussed how sand bag fill levels (hard vs. soft) can affect accuracy. Speedy says you don’t want to have both your front and rear sandbags filled up ultra-hard. One or the other bag needs to have some “give” to provide a shock-absorbing function (and prevent stock jump).
SAND BAGS & HOW TO FILL THEMby Speedy Gonzalez
I was asked several times by competitors at the S.O.A. Matches and F-Class Nationals as to how I fill my sand bags for benchrest competition. Here is a copy of a reply I gave several years ago:
Back in the old days, about the time Fred Flintstone was still alive, I worked for Pat McMillan for free, from time to time to learn all his secrets. One day little Speedy was filling some new sand bags out behind Pat’s shop, stuffing them with more sand than Taco Bell put beans in their Burritos. When Pat stepped out the back door and inquired as to what in the hell was I doing packing them there bags the way I was.
I looked up at him with eyes like a kid with his hands in a cookie jar. My reply must have sounded like Homer Simpson “Doooh”. Finally I said “I don’t know, Boss. I just thought you were supposed to fill these babies up and go shoot. I got that ‘You dumb bastard look’ from Pat and I knew it was lecture time. This was what he told me:
You can not have two bags filled so hard that you gun bounces on them in the process of firing round at your target, especially if you have a rig with a very flexible stock. The bags must be set up in a manner for them to absorb the initial shock of the firing pin moving forward and igniting the primer. Then [they must] maintain their shape and absorb the second shock wave as well the rearward thrust and torque of the rifle. What happens to the rifle when this is not done? Well let me tell you. The rifles have a very bad tendency to jump and roll in the bags. This causes many of those wild, lost shots that one can’t explain.
Charles Huckaba, Ken Terrell, Larry Baggett, Ralph Stewart and some of us Texas shooters talk about this phenomena quite often. We have all agreed that:
1: You can not have two hard bags [i.e. both front AND rear] in your set-up.
2: Heavy sand magnifies these phenomena.
3: If you are a bag squeezer, pack ears hard and leave bag pliable enough to squeeze for the movement required. You may pack front bag as hard as rules permit.
4: Free recoil shooters pack both bags firm, but not so hard as to allow stock jump. Especially if you have a stock with a very flexible forearm.
5: We use play-ground sand, also know as silica sand. I sift mine to get any large impurities out then mix it with 25% to 50% with Harts parakeet gravel to the desired hardness that I am looking for. The bird gravel keeps the sand from packing itself into that solid as a brick state.
Speaking of bricks — another thing that happens when shooters employ that heavy zircon sand is the ears form a low spot under them from recoil and then tend to rock back and forth with the rifle causing many low shots to crop up. Edgewood makes an Edgewood/Speedy rear bag specially reinforced under the ears to eliminate this scenario.
One last note –If you use the Cordura bags keep them sprayed with a good silicon spray or “Rain-Ex”. This keeps them from getting sticky. Hey guys, try that and see if it helps. — Speedy
P.S.: I do not like the solid double-stitched leather bottoms. While this seems like a good idea, I see more shooters have problems because of them. They tend to slide around the bench and or slide with the rifle on recoil. The standard Protektor with Cordura rabbit ears and an Otto ring bag with a Cordura front would be what I would suggest to the new shooter or one of the Edgewood / Speedy rear bags, these mimic the “Donut” and feature a ring of leather around the bottom circumference that keep the bottom from rocking on the bench or ground if that is where you reside these days…
Share the post "Tuning Your Sandbag Hardness — Tech Tip by Speedy"
Hearing loss can be progressive and irreversible. If you are a shooter, this is serious business. You need to use effective hearing protection every time you go to the range. Even if you are away from the firing line, gunshot noises can damage your hearing. Good foam earplugs costs mere pennies but they can prevent deafness in your later years. Many folks also wear muffs over plugs. Some other shooters prefer the custom-molded ear plugs. Electronic muffs can be useful when you are away from the firing line because they allow you to converse.
Here are some comments from Forum members on the subjects of hearing loss and the need for proper ear protection. You can join the discussion in this FORUM THREAD:
“If you are young and don’t want to end up with profound hearing loss like I have… ALWAYS ALWAYS ALWAYS use hearing protection. This is from a guy who is social security/medicare eligible, has two Re-Sound aids at a not so cheap $2000.00 EACH… and now has religion! When I was young [we] never wore ear gear and laughed at the ringing after 100 rounds of 12 gauge at the skeet range. Now we live with the consequences. Be smarter than I was!” — Gary0529
“Take it from a 70-year-old that has been shooting 49 years. I now have a Re-Sound hearing aid in the left ear and a Cochlear Implant in my right. I still cannot hear. Custom molded plugs are best. Some are sold at gun shows and some are made by the folks that make hearing aids. They are cheap as compared to this $200,000 implant. DO IT NOW for everyone around guns.” — Richard King, King’s Armory
“Say WHAT? You have to type a little louder! I used to shoot without any muffs, when I was ‘young and indestructible’, and now I have about 40% loss. When I take youngsters and friends shooting, they get muffs and plugs. I’m not allowed suppressors where I live. I would use them if I could.” — Josh B.
“For what it’s worth, I wear both ear plugs and muffs that have NO sound adjustment capability. As a youngster (15) I wore no ear protection either in shooting or motorcycle riding. I kept doing that until entering military service at age 18 where we had to wear ear plugs at the range. Started wearing ear plugs after that, except when motorcycle riding. At around age 53 my hearing started going south as a result of my own stupidity as a youngster and now some 15 years later I only have about 45% of my hearing left. So beware all — there is a price to pay if you don’t protect your hearing.” — Shynloco
“Here are several points to consider:
1. The NRR (noise reduction rating) is determined by “experimenter” fit, not user fit, and trained listeners during the testing period. This results in inflated protection numbers compared to real-world protection.
2. Any disruptions in the protector/skin seal will greatly reduce the effectiveness. Think eye glass temple bars, lots of hair, ear wax, etc. A 5% leak results in a 50% reduction in effectiveness.
3. Double protection gives only 5-10 dB extra protection.
4. Bone conduction gives about 50 dB protection so hearing protectors are the weak link[.]
5. Keep the protectors in/on your ears. Over 8 hours, if you remove them for only 30 minutes (cumulative), the effective protection is cut in half.
So, if you are using a really good muff with NRR of 33 and a foam plug with NRR of 27, the real-world NRR would be about 35 dB, at best. This would attenuate a gunshot by that amount. The key is time versus exposure. Limit the exposure and you limit the dose.” — DelS
“Personally, I use Etymotic Research GSB-15 electronic blast protectors. They are rated at 26-28 dB, but inserted correctly, with the correct fitting tip, approach 38 dB. And, they have a compressor amplifier that allows you to hear soft sounds normally and with very high fidelity. As the sound level goes up, the gain goes down till at an ambient sound pressure level of around 90 dB SPL, the gain is unity, or what comes in goes to the ear canal. However, once the sound level gets to 117dB SPL, the amplifier cannot go higher. So, if you are firing a large rifle with an impulse noise of around 160 dB SPL, your ear only hears 117 dB SPL of that for an effective attenuation of about 40 dB. RIGHT! about the same as the mastoid bone! Can’t get any better than that.
What gives me the right to say all these things? First, a BSEE as well as the graduate course in Audiology and a hearing aid dispensers license. And working in research and product development for the ear the last decade of my career.” — Norm Matzen
Share the post "“Say What?” — Forum Members Talk About Hearing Loss"
Sinclair International has created a series of instructional videos illustrating the basics of metallic cartridge reloading. The 8-part series starts with reloading basics and provides step-by-step, how-to instructions that will help new reloaders get started. Detailed, animated illustrations show you what happens inside the chamber when shooting, and inside the dies during each step of reloading. The videos can be viewed on Sinclair Int’l’s YouTube page. Shown below is the first video in the series:
Each of the eight videos is hosted by Sinclair Int’l President Bill Gravatt. Bill doesn’t just show you “how”, he tells you “why”. The how-to segments cover case inspection, proper die set up, case sizing, primer installation, powder measuring, bullet seating, crimping, and even goes into the record keeping needed for the handloader. “We wanted to give shooters who haven’t reloaded a look at all the advantages of creating your own ammo and how easy it is to get started,” said Gravatt, “without telling them they had to have any certain brand or type of equipment to do the job.” The eight videos are:
Part 1 — Intro to Video Series
Part 2 — Intro to Reloading Safety
Part 3 — Metallic Cartridge Components
Part 4 — The Firing Sequence
Part 5 — Tools for Reloading
Part 6 — Loading Bottle-Neck Cartridges
Part 7 — Loading Straight Wall Cartridges
Part 8 — Reloading Series Conclusion
Shown below is Part 5 of the video series, covering the tools used for precision reloading.
Share the post "Sinclair Int’l Offers 8-Part Series of Reloading Videos"
These days, a smartphone is an indispensable tool for a serious shooter. Smartphones can forecast the weather, direct you to the range, map your terrain, calculate your ballistics, photograph your targets, and even measure wind velocity (with a $35.00 plug-in impeller).
Having all those capabilities is great… until your battery goes flat. Even the most advanced smartphone on the planet is nothing but a useless paperweight when you run out of juice. Thankfully there’s an affordable fix for that problem — back-up Li-ion battery packs with built-in solar chargers.
There are a variety of external power-packs on the market, some with solar panels, some without. These will charge smartphones, tablets, PDAs, and other mobile devices. We like the units with solar chargers because they can recover a little energy when you’re outdoors. You still need to plug them in to get a full charge BEFORE before you head to the range. But once fully charged, these back-up battery devices can get your smartphone back in action and keep it running all day long.
We like the Poweradd portable chargers*. These feature lithium-ion batteries, solar panels, and tough weatherproof shells. We’ve tried two models, the 8000 mAh Apollo 3 ($29.99, dual-port), and the original 7200 mAh Apollo ($19.99, single port). We purchased the 7200 mAh Poweradd (Photo above) before its third-generation bigger brother was offered. The original 7200 mAh Apollo has served us well. It can fully charge most smartphones a couple times, or smaller tablets once. As long as you make sure the Poweradd is fully charged before you leave home (since the solar charger is slow and secondary), this unit does everything it claims. This editor’s first-generation Poweradd Apollo has done yeoman duty for many months now. It has revived both an iPhone and a tablet. If I were to purchase a Poweradd unit now, I would get the Apollo 3, mainly because it offers two (2) charging ports compared to one (1) on the original Apollo. That lets you charge two devices at once.
* If you need even more power, consider the Poweradd Pro. This 23000 mAh powerpack offers Multi-Voltage (5V 12V 16V 19V) output, and has enough juice to run a modern laptop. It comes with a complete set of jacks/cables so it can work with almost any device. This kind of capability doesn’t come cheap — the Poweradd Pro sells for $109.99, more than five times the cost of our 7200 mAh Apollo.
Share the post "Juice on the Go for your Smart Phones and Mobile Devices"
We know many of our readers live on farms or ranches. When driving around these properties you may want to keep a firearm handy for pest control or to deal with feral animals. If you live in the country, chances are good you have utility vehicles — such as ATVs, Gators or tractors — and transporting guns safely to allow for easy access is essential. In this video, American Handgunner magazine Editor Roy Huntington highlights some inexpensive solutions for safely transporting guns on various outdoor utility vehicles. Roy shows set-ups for an E-Z-Go Cart, a Honda 4×4 ATV, and a John Deer tractor. Of course, as Huntington explains, always practice the four firearm safety rules. Roy cautions that you should never transport a shotgun or rifle with a round in the chamber, and be very careful when getting in or out of the vehicle if you have a gun in your hands.
New Polaris ATV Features Non-Pneumatic Tires
If you’re thinking about buying a ranch or hunting vehicle, here’s something to drool over — the new Sportsman WV850 H.O. from Polaris. This hard-working ATV features non-pneumatic tires, which employ a lattice structure developed for the U.S. military. The Sportsman WV850 H.0. features 600-lb load-carrying capacity (on stout steel racks), power steering, and a massive 11.75 gallon gas tank. That’ll get you out into the backwoods!
American Handgunner video find by EdLongrange. We welcome reader submissions.
Share the post "Transporting Firearms on Farm, Field, and Ranch Utility Vehicles"
It’s summer time. That means many of our readers will be hitting the road (for matches at Camp Perry or summer vacations). How do you do your reloading chores while living like a Gypsy for a few weeks? Here’s a solution from Forum member Dave Gray (U.S. Army Retired).
Dave is a self-declared “full-time RVer” who spends most of his time on the road. Behind his Ram 3500 pickup, Dave tows a huge 41-foot Heartland Cyclone toy hauler featuring a 12X8 foot garage in the rear. In the rear garage area, which holds a Smart Car, Dave has set up a removable reloading bench complete with RCBS Rockchucker single stage press and Dillon progressive press.
Reloading Bench Mounts to RV Wall with Brackets
Dave explains: “I used a 2″X6″X5′ board for the bench. It’s perfect for my needs, and is easy to disassemble. I made it this small so that I can park my Smart Car in the garage during travel to my destinations. The bench, attached to the wall frames, is very solid. The presses’ centers are 3″ and 6.5″ from the brackets. [There are] four bolts on the wall into aluminum wall frame and 3 bolts in the bench. If I ever have to replace the current board, I’ll do so with oak or birch or hickory. When I’m not reloading, I remove the presses and store them in a protected space. I can easily attach other equipment to the bench by using C-Clamps.” Dave’s “rolling reloading room” looks very well thought-out. We commend Dave for his inventiveness.
Share the post "Goin’ Mobile — Reloading Set-Up for Toy-Hauler RV"
Most competitive shooters are pretty good about bore cleaning (some may even clean their bores too aggressively). However, we’ve found that many shooters neglect the chamber area and the bolt lug recesses. It’s too easy to clean the bore, slip out the guide rod and say “I’m done.” Sinclair Int’l explains why it’s important to clean the action interior: “Shooters use a lot of grease and oil on their bolts to reduce friction and to prevent wear[.] Unfortunately, both of these compounds attract grit, powder and primer residues. Cleaning your receiver is especially critical [with] custom actions where the fit between the action and bolt is held to very tight tolerances. Routine cleaning of the action will prevent unnecessary wear on the bolt body, locking lugs, and the action raceways/guide rails. Frequent action cleaning is also essential to keeping the trigger area free of debris which can cause trigger hang-ups and failures.” Below, we present action cleaning advice from Sinclair’s Reloading Press Newsletter.
Cleaning the Chamber
Combustion by-products, lubricants, and solvent residues can collect in your chamber. Severe build-up of grease and carbon can interfere with chambering. Also some solvents will promote corrosion. You need to keep your chambers clean.
1) Install a clean cotton mop of the correct size on the end of a chamber rod and insert the mop into the chamber. Rotate the mop several times to remove any brush bristles left behind and any excess solvent that was between the rod guide snout and the end of the chamber. Make sure the chamber is dry. Prior to storing a rifle you can oil the chamber but make sure the oil is removed prior to firing the rifle.
2) Alternatively, install an old bore brush on a chamber rod, overlap a couple of patches on the brush bristles, and wrap them around the brush completely. Then insert the patch-covered brush into the chamber while rotating it to remove the excess solvent and debris. Push it firmly into the neck area of the chamber. A similar method is to pierce a large patch on the end of the brush loop and insert it into the action, again rotating the brush as you push the patch up against the breech.
Cleaning the Lug Recess Area
The action lug recess area is one of the dirtiest places on a bolt-action rifle. To properly clean this area, always use a tool designed for the task, such as the $21.50 Sinclair Action Cleaning Tool (part # ACT1) which is part of the Sinclair Action Cleaning Tool Kit (now on sale for $29.99, part #ACT2).
1) Insert a cotton roll or cleaning felt into your lug recess cleaning tool and wet both ends and the face of the cotton roll/felt with solvent.
2) Insert the tool into the action and push it forward until it is positioned fully in the lug recess area and rotate the tool head several times. Then reverse the rotation for another few turns. While rotating the tool move it slightly in and out to cover the entire recess area and to also clean the breech face.
3) Remove the tool from the action and inspect the surface of the felt or cotton roll. If there is quite a bit of residue on both sides of the felt/roll, then repeat with another wet felt/roll.
4) When you feel the recess area is completely clean, insert a dry cotton roll into the tool and rotate the tool head to remove any remaining solvent and debris. If necessary, use a second dry cotton roll.
5) You can follow this step up with another pass of a mop or patches into the chamber to get any debris or solvent that pushed forward out of the lug recess area.
Most of us have access to a printer at home or at work. That means you can print your own targets. You’ll find hundreds of free target designs online, including dozens of downloadable targets on our AccurateShooter.com Target Page. If you’re feeling creative, you can design your own target with a computer drawing program such as MS Paint.
Paper Stock Is Important
If you want your self-printed targets to show shots cleanly (and not rip when it gets windy), you should use quality paper stock. We recommend card stock — the kind of thick paper used for business cards. Card stock is available in both 65-lb and 110-lb weights in a variety of colors. We generally print black on white. But you might experiment with bright orange or yellow sheets. Forum Member ShootDots report: “They sell cardstock at Fed-Ex Kinko! I use either Orange or Yellow. That makes it easy to see the bullet holes clearly.” On some printers, with the heavier 110-lb card stock, you will need to have the paper exit through the rear for a straighter run.
Here are some Target-Printing Tips from our Forum members:
“Staples sells a 67-lb heavy stock that I have settled on. I use the light grey or light blue, either of these are easy on the eyes on bright days. I have used the 110-lb card stock as well and it works fine. It’s just a little easier to print the lighter stuff.” (JBarnwell)
“Cardstock, as mentioned, works great for showing bullet holes as it doesn’t tear or rip like the thin, lightweight 20-lb paper. I’ve never had a problem with cardstock feeding in the printer, just don’t stick too many sheets in there. If I need three targets, I load only three card stock sheets”. (MEMilanuk)
“I’ve used Staples Sticker paper. This works well and no staples are required (joke intended). It helps if you put slight tension on the lighter weight paper when mounting it on the target frame.” (Mac 86951).
Here are some tips for using lighter weight paper (if you want to save money or your printer won’t work with heavier stock):
“20-lb bond works pretty well for me if I use a spray adhesive and stick the entire back of the paper’s surface to the backer board.” (Lapua40X)
“I use the regular 20-lb paper but the only time it tears is when there is no backer to support it. This can be an issue when going to a public range and the backer are all shot out. I use a large construction paper backer that I clip onto the stands.” (CPorter)
Here Are Three of Our Favorite Targets. Click to Download PDFs.
Share the post "Tech Tip: How to Print Better, More Durable Targets"
In the video below, Forum Member Thomas Haugland (from Norway) shows how to install a Picatinny-type rail on a Sako action. Every stage of the process is illustrated — removing the barrel from the action, drilling/tapping the action, aligning/attaching the rail, and finally mounting the scope and test-firing the rifle. Note that the action is removed using a large adjustable-end wrench with brass disks to protect the finish. This is possible because this particular Sako action has a flat bottom and top. With a different action you’ll want to use a custom action wrench.
In the video, Thomas and his assistant actually fabricate the rail from scratch. That’s probably beyond the ability of most do-it-yourselfers. You can purchase precisely machined Picatinnny rails from Seekins Precision and other sources instead. Still, it is interesting to see the milling of the rail. Note that, before screwing the rail to the top of the action, Thomas applies a marine epoxy (timeline 3:18). This effectively beds the rail to the top of the action and provides a more secure installation.
You can find more interesting gunsmithing, hunting, and long-range shooting videos on Thomas Haugland’s YouTube Channel.
Share the post "Gunsmithing: Installing a Picatinny Rail"
With barrels, one always wonders “Can a little more length provide a meaningful velocity gain?” To help answer that question, Rifleshooter.com performed an interesting test, cutting the barrel of a .223 Rem rifle from 26″ all the way down to 16.5″. The cuts were made in one-inch intervals with a rotary saw. At each cut length, velocity was measured with a Magnetospeed chronograph. To make the test even more interesting, four different types of .223 Rem/5.56 ammo were chron’d at each barrel length.
Test Barrel Lost 25.34 FPS Per Inch (.223 Rem Chambering)
How much velocity do you think was lost, on average, for each 1″ reduction in barrel length? The answer may surprise you. The average speed loss of the four types of .223/5.56 ammo, with a 9.5″ shortening of barrel length, was 240.75 fps total (from start to finish). That works out to an average loss of 25.34 fps per inch. (See inch-by-inch data HERE.)
5.56/.223 Barrel Cut-Down Speed Test 26″ to 16.5″
Start FPS at 26″
End FPS at 16.5″
Average Loss Per Inch
UMC .223 55gr
Federal M193 55gr
Win m855 62gr
Blk Hills .223 68gr
*There may have been an error. The 25″ velocity was higher at 3221 fps.
Rifleshooter.com observed: “Cutting the barrel from 26″ to 16.5″ resulted in a velocity reduction of 214 ft/sec with the UMC 223 55-grain cartridge, 244 ft/sec with the Federal M-193 cartridge, 288 ft/sec with the Winchester M855 cartridge and 217 ft/sec with the Back Hills 223 68-grain match cartridge.”
How the Test Was Done
The testers described their procedure as follows: “Ballistic data was gathered using a Magnetospeed barrel-mounted ballistic chronograph. At each barrel length, the rifle was fired from a front rest with rear bags, with five rounds of each type of ammunition. Average velocity and standard deviation were logged for each round. Once data was gathered for each cartridge at a given barrel length, the rifle was cleared and the bolt was removed. The barrel was cut off using a cold saw. The test protocol was repeated for the next length. Temperature was 45.7° F.”
Much Different Results with 6mmBR and a Longer Barrel
The results from Rifleshooter.com’s .223/5.56 test are quite different than the results we recorded some years ago with a barrel chambered for the 6mmBR cartridge. When we cut our 6mmBR barrel down from 33″ to 28″ we only lost about 8 FPS per inch. Obviously this is a different cartridge type, but also our 6mmBR barrel end length was longer than Rifleshooter.com’s .223 Rem start length. Velocity loss may be more extreme with shorter barrel lengths.
Share the post "Surprising Results in .223 Rem Barrel Cut-Down Velocity Test"
Each Wednesday, the U.S. Army Marksmanship Unit publishes a reloading “how-to” article on the USAMU Facebook page. Yesterday’s post covered primer seating depth. This article offers many useful tips — including a clever way to measure primer seating depth with ordinary jaw-type calipers. Visit the USAMU Facebook page next Wednesday for the next installment.
Primer Seating Depth — Why Uniformity is Important
The first concern is for safety: for that reason, primers should be seated below flush with the case head. One primary cause of “slam fires” (which includes catastrophic failures from firing out of battery) is “high,” or protruding primers. These stand above the case head, are readily felt with simple finger-tip inspection, and may fire when slammed by the bolt face and/or a floating firing pin in feeding.
Here at the USAMU, we ensure our rifle primers generally run -0.003″ to -0.005″ below the case head. Maximum primer depth is -0.006″ and minimum is -0.002″. Upon inspection, any cases with high primers will be corrected before loading. Aside from improving ballistic uniformity, ensuring the primers have proper compression upon seating also helps reduce possible misfires. These can be caused by the firing pin’s expending part of its energy either seating the primer or having to deform the primer cup enough to reach the anvil.
SMART TIP: How to Measure Primer Seating Depth with a Set of Calipers
A zeroed, precision set of standard calipers will also measure primer seating depth. (You don’t really need a custom tool.) Merely close the jaws and place the calipers’ narrow end squarely across the center of the case head/primer pocket. Keeping the narrow end in full contact with the case head, gently open the jaws, and the center bar will extend until it reaches the primer face. Voilà! Primer depth is read on the dial. Taking a few measurements to ensure accuracy and repeatability is recommended until one is familiar with this technique.
Brass and Primer Defects Can Cause Seating-Depth Variances
Factors affecting variance of primer seating depth include brass maker and lot number — all primer pockets are not created equal! Another factor is the primer manufacturer and individual primer lot. We’ve encountered occasional primer lots by top-quality makers that included some primers with slight defects affecting seating. While finely accurate, these primers were out-of-round or had small slivers of cup material protruding which affected primer feeding or seating depth.
Has one’s brass been fired previously? If so, how many times and the pressures involved also affect future primer seating. Obviously, this is another factor in favor of segregating one’s high-accuracy brass by maker, lot number, and number of times fired, if possible.
Measuring Primer Seating Depth with Purpose-Built Gauge
The next question, “How do we measure primer depth?” happily can be answered using tools already owned by most handloaders. [See tip above on how to measure depth with calipers.] At the USAMU, we have the luxury of purpose-built gauges made by the talented machinists of the Custom Firearms Shop. One places the primed case into the gauge, and the dial indicator reads the depth quickly and easily. The indicator is calibrated using a squarely-machined plug that simulates a case head with a perfectly flush-seated primer, easily giving meaningful “minus” or “plus” readings. The gauge is usable with a variety of case head sizes.
Primer Seating with Progressive Presses
Methods of primer seating include hand-seating using either hand held or bench-mounted tools, vs. progressive-press seating. Progressive presses may either seat by “feel,” subjective to each operator, or by using a mechanical “stop” that positively locates primers nearly identically every time. Testing here has shown that we get more uniform seating with the latter type progressive press, than we do with a high-quality bench-mounted tool lacking a positive stop.
Primer stop depth adjustments on our main progressive presses involve turning a punch screw in and out. While the screw is not calibrated, fine “tick” marks added to the top of the press help users gauge/repeat settings by “eye” efficiently with practice. Then, once a sample of primed cases is run to confirm the range and accuracy of depths, the identifying lot number and maker is noted on the press for reference. When it’s necessary to switch brass/primer lots, changes are easy to make and settings are easily repeated when it’s time to switch back.
Share the post "Primer Seating Depth Uniformity and Accuracy"
This is a message to my friends in the shooting community: be careful with your skin. I wasn’t careful enough and now I have skin cancers. When the Doctor says the “C” word, trust me, it’s a scary thing. That’s me in the photo below. The reason I have band-aids on my cheek and my chest is that I was just diagnosed with multiple basal cell carcinomas (the band-aids cover biopsy sites). These basal cell cancers can (and will) be surgically treated, but any skin cancer is worrisome. The worst kind of skin cancers, melanomas, can be fatal if not detected very early.
An Ounce of Prevention — How to Protect Your Skin
Fellow shooters, my message to you is: Protect your skin… and see a dermatologist regularly. If you are over 40 and have spent a lot of time outdoors, I suggest you see a skin doctor every year.
As gun guys (and gals) we spend a lot of time outdoors, much of it in bright sunlight. When working and playing outdoors, you should always try to minimize the risk of skin damage and possible skin cancers. Here are some practical tips:
1. Wear effective sunscreen. Get the kind that still works even if you sweat.
2. Wear a wide-brimmed hat and quality sunglasses with side protection.
3. Protect your arms and neck. It’s smart to wear long-sleeve shirts with high collars. There are “breathable” fabrics that still offer good sun protection.
4. Stay in the shade when you can. Direct sunlight is more damaging to your skin.
5. When testing loads or practicing you can make your own shade with an umbrella fixed to a tripod or scope stand. This has the added benefit of keeping you (and your ammo) cool.
6. Do a “field survey” of your skin every few weeks. Have your spouse or “significant other” inspect your back and the backside of your legs.
What to Look For — How to Spot Possible Skin Cancers
Here is an illustration that shows various types of skin cancers. But understand that an early basal cell carcinoma can be much, more subtle — it may just look like a small, pale pink spot. Also, if you have a scab that flakes off and re-appears, that might be a cancer. In the case of the basal cell on my face, I initially thought it was just a shaving abrasion. The skin was just slightly pinkish, with a little scab that would form and come back. But after a couple months, it never got any better. That’s what prompted me to see the doctor. And I’m glad I did….
Share the post "When the Doctor Says the “C” Word — Skin Cancer and Shooters"
Some of our readers have questioned how to set up their body dies or full-length sizing dies. Specifically, AFTER sizing, they wonder how much resistance they should feel when closing their bolt.
Forum member Preacher explains:
“A little resistance is a good, when it’s time for a big hammer it’s bad…. Keep your full-length die set up to just bump the shoulder back when they get a little too tight going into the chamber, and you’ll be good to go.”
To quantify what Preacher says, for starters, we suggest setting your body die, or full-length sizing die, to have .0015″ of “bump”. NOTE: This assumes that your die is a good match to your chamber. If your sizing or body die is too big at the base you could push the shoulder back .003″ and still have “sticky case” syndrome. Also, the .0015″ spec is for bolt guns. For AR15s you need to bump the shoulder of your cases .003″ – .005″, for enhanced reliability. For those who have never worked with a body die, bump die, or Full-length sizing die, to increase bump, you loosen lock-ring and screw the die in further (move die down relative to shell-holder). A small amount (just a few degrees) of die rotation can make a difference. To reduce bump you screw the die out (move die up). Re-set lock-ring to match changes in die up/down position.
That .0015″ is a good starting point, but some shooters prefer to refine this by feel. Forum member Chuckhunter notes: “To get a better feel, remove the firing pin from your bolt. This will give you the actual feel of the case without the resistance of the firing pin spring. I always do this when setting up my FL dies by feel. I lock the die in when there is just the very slightest resistance on the bolt and I mean very slight.” Chino69 concurs: “Remove the firing pin to get the proper feel. With no brass in the chamber, the bolt handle should drop down into its recess from the full-open position. Now insert a piece of fire-formed brass with the primer removed. The bolt handle should go to the mid-closed position, requiring an assist to cam home. Do this several times to familiarize yourself with the feel. This is how you want your dies to size your brass, to achieve minimal headspace and a nearly glove-like fit in your chamber.”
We caution that, no matter how well you have developed a “feel” for bolt-closing resistance, once you’ve worked out your die setting, you should always measure the actual amount of shoulder bump to ensure that you are not pushing the shoulder too far back. This is an important safety check. You can measure this using a comparator that attaches to your caliper jaws, or alternatively, use a sized pistol case with the primer removed. See Poor Man’s Headspace Gauge.
Share the post "Tech Tip: Shoulder Bump — How Much Is Enough?"
Horizontal Wind-Drift vs. Distance
OK, here’s a challenge question for you.
Let’s see if you get it right.
Q: If the wind is blowing 10 mph from 9 o’clock and if my horizontal wind deflection is 0.7 inches at 100 yards, what is the horizontal drift at 1000 yards?
You may be thinking, “Well, since the target is ten times more distant, the wind-drift should be around 7 inches, maybe a little more since the bullet will be slowing down.” That sounds reasonable, right?
As you move from near to far, the increase in lateral deflection (from a 90° crosswind) is (roughly speaking) a function of the square of the multiple of distance. If your target is two times farther away, you use the square of two, namely four. If your target is five times farther away, you use the square of five, or twenty-five. In this example, the increased wind drift (from 100 to 1000 yards) is at least 0.7″ times (10 X 10) — over 70 inches (give or take a few inches depending on bullet type). We call that the Rule of the Square. This Rule lets you make a quick approximation of the windage correction needed at any yardage.
Precision Shooting and the Rule of the Square
I was going through some back issues of Precision Shooting Magazine and found many references to the Rule of the Square. This made me curious — I wondered how well the Rule really stacked up against modern ballistics programs. Accordingly, I ran some examples through the JBM Ballistics Trajectory Calculator, one of the best web-based ballistics programs. To my surprise, the Rule of the Square does a pretty good job of describing things.
EXAMPLE ONE — .308 Win (100 to 400 Yards)
For a 168gr Sierra MK (.308), leaving the muzzle at 2700 fps, the JBM-predicted values* are as follows, with a 10 mph, 9 o’clock crosswind (at sea level, 65° F, Litz G7 BC):
Drift at 100: 0.8 MOA (0.8″)
Drift at 200: 1.6 MOA (3.3″)
Drift at 400: 3.4 MOA (14.4″)
Here you can see how the Rule of the Square works. The rule says our drift at 200 yards should be about FOUR times the drift at 100. It the example above, 0.8″ times 4 is 3.2″, pretty darn close to the JBM prediction of 3.3″. Quoting Precision Shooting: “Note that the deflections at 100 yards are typically a quarter of those at 200; lateral deflections increase as the square of the range”. Precision Shooting, June 2000, p. 16.
EXAMPLE TWO — .284 Win (100 to 1000 Yards)
For a .284 Win load, with the slippery Berger 180gr Target Hybrids, the Rule of the Square still works. Here we’ll input a 2750 fps velocity, Litz G7 BC, 10 mph, 9 o’clock crosswind, (same 65° temp at sea level). With these variables, JBM predicts:
Drift at 100: 0.5 MOA (0.5″)
Drift at 500: 2.5 MOA (13.3″)
Drift at 1000: 5.9 MOA (61.3″)
Again, even with a higher BC bullet, at 1000 yards we end up with something reasonably close to the 100-yard deflection (i.e. 0.5″) multiplied by (10×10), i.e. 50 inches. The Rule of the Square alerts you to the fact that the effects of crosswinds are MUCH greater at very long range. In this example, our JBM-calculated drift at 1000 is 61.3″ — that’s over 100 times the 100-yard lateral drift, even though the distance has only increased 10 times.
Note that, even with a 5 mph 90° sidewind, the “Rule of the Square” still applies. The 1000-yard lateral deflection in inches is still over 100 times the lateral deflection at 100 yards.
Why This All Matters (Even in the Age of Smartphones)
Now, some would say, “Why Should I Care About the Rule of the Square? My iPhone has a Ballistics App that does all my thinking for me”. Fair enough, but knowledge of this basic Rule of the Square enables a shooter to make an informed guess about necessary windage even without a come-up sheet, as long as he knows the distance AND can fire a sighter at 100 or 200 yards as a baseline.
For example, if I see empirically that I need 1″ windage correction at 100 yards, then I know that at 600 yards I need at least roughly (6 x 6 x 1″) or 36 total inches of drift correction, or 6 MOA. (To be precise, 1 MOA = 1.047″ at 100 yards). I can figure that out instantly, even without a ballistics chart, and even if my Smartphone’s battery is dead.
*Values shown are as displayed on the JBM-figured trajectory tables. The numbers can be slightly imprecise because JBM rounds off to one decimal place for both inches and MOA.
Share the post "Brain Teaser: Do You Know the Rule of the Square?"
Many shooters are familiar with ballistics tables, weather programs, and even wind meters for smart devices, but few may know about a very handy Leveling Tool that comes factory-installed on Apple iPhones. The leveling function is a little-known option in Apple’s Compass App. It works well for a multitude of tasks.
There are a numerous reasons that a leveling tool should be in every rifleman’s range bag. From leveling optics during mounting to figuring out how much extra compensation is going to be required for a tricky angled shot, knowing just how far off things are from plumb can go a long way towards realizing success in the field.
This writer has used the leveling app on his iPhone to level a rifle on a rest while at the range. It definitely worked for “field expedient” leveling duties. That’s especially important for long-range applications. Just one degree of cant (tilt) can move your point of impact 7 inches at 1000 yards.
Of course, the iPhone level doesn’t use an actual bubble to find angles. Rather, it relies on the device’s sophisticated accelerometer to do so, and with a great degree of accuracy. Navigating to the level is done by first selecting the Compass App, at which point the device will need to be calibrated by rotating it a full 360 degrees. Once the compass is fully calibrated, simply make right swipe gesture to bring up the level — it will start operating immediately.
From there, use is intuitive and easy, like most iPhone Apps. Switching from horizontal plane to vertical is done by simply changing the physical axis of the phone. How do you know when you’ve got things just right — well the entire lower half of the screen turns green when everything is perfectly level. You’ll also see a zero° read-out, like this:
Bottom Line: If you already own an iPhone, you should definitely give this App a try. The price is right (free), and for a wide variety of tasks the iPhone Level App is actually pretty handy.
Share the post "Tech Tip: Use Your iPhone as a Leveling Device"