October 23rd, 2014

Ultrasonic Case Cleaning — How to Get Better Results

Sooner or later you’ll want to clean your rifle brass, even if you aren’t fussy about appearance. You can tumble your cases in a vibratory tumbler with dry media, but that can leave cases with a fine layer of dust, or worse yet, clogged flash holes. As an alternative to tumbling, many shooters are experimenting with ultrasonic case cleaning. Here are three tips to achieve the best results when using ultra-sound to clean your brass:

Try a Commercial Ultrasonic Cleaning Solution
As a companion product to its new ultrasonic cleaning tank, Hornady is selling a citric-acid based One Shot™ Sonic Clean™ Solution, that is claimed to speed up cleaning times, and not leave your brass an odd pinkish color like some “home-brew” solutions. We’ve heard good reports about the One-Shot Solution (cartridge case formula) as well as Citranox®. Both products are economical to use since you dilute them heavily with water. For example, Hornady recommends you mix forty (40) parts water to one part of One Shot Sonic Clean.

Ultrasonic Cleaning Solutions

Forum member Dave B is a chemist/physicist with decades of experience working with the ultrasound process. Dave tried a variety of solutions and he favors a mix of water and Citranox®. Dave notes: “So far I’ve been very impressed with the Citranox. Once- or twice-fired brass clean up very quickly. The worst cases I tried were 6 Dashers that had been fired ten times with Varget and never cleaned. The worst fouling was in the bottom of the case around the flash hole. They took longer and I used a more concentrated cleaning solution but they did come out clean. The price is reasonable. I paid $35 a gallon and for once- or twice-fired cases I dilute the cleaner 100 to 1. There is much less chemical reaction with the brass than there is with vinegar. No weird colors, just shiny bright. I even used it with hot water, which speeds up the cleaning process. The cleaner is mostly detergents with a little citric acid. Even at a 1:75 ratio my $35 worth of cleaner will make 75 gallons of solution.” The price has gone up a bit since Dave acquired his Citranox, but Amazon.com sells Citranox for $45.50 per gallon.

Another good ultrasonic solution is L&R non-ammoniated Safety Cleaning Solution, sold by Brownells, item #515-000-004. Brownell’s L&R solution is non-toxic and biodegradeable. The strong surfactant in L&R solution helps penetrate the grit so the ultrasonic cavitation can carry the grime away.

De-Gas the Solvent Before Adding Brass
One of our readers, Eddy M. in Glasgow, Scotland writes: “I have read a couple of articles recently about ultrasonic cleaning of cases and not one has mentioned de-gassing the cleaning liquid before starting to clean items. As an engineer who traveled around for ten years servicing ultrasonic tanks I would like to point out that the cleaning liquid when first put into the tank has invisible dissolved air bubbles in it which will absorb ultrasonic energy until the liquid de-gasses. (Ten minutes in a powerful industrial tank — longer in a small hobby tank). You must let the tank run on its own for 20 minutes on the first use of the liquid to allow this to happen. Only after the new liquid or re-introduced liquid has been de-gassed will the tank give good results.”

moly dry lube kit NeconosApply Dry-Lube Inside Case Necks
Jason Baney has found that Ultrasonic cleaning leaves the inside of the case-necks so “squeaky clean” that there is excess friction when seating bullets. On a fired case that has been cleaned conventionally (no ultra-sound), a thin layer of carbon remains to lubricate the bullet entry and exit. To restore that lubricity in cases cleaned with ultrasound, Jason applies a dry lube to the inside of his case necks. Jason prefers the $10.95 moly dry lube kit from Neconos.com. With this kit, small carbon steel balls transfer moly to the neck when you place your brass nose-down in the container.

Permalink Reloading, Tech Tip 5 Comments »
October 22nd, 2014

Storage Sacks for Firearms in Your Safe

Bore-Store Gun SacksOur take on Bore-Store Gun sleeves is simple: They work great, so buy them and use them — for ALL your valuable firearms.

These thick, synthetic-fleece sacks cushion your guns, preventing nicks and scratches. The breathable fabric wicks away moisture, and the fibers are coating with corrosion inhibitors. I personally use Bore-Stores for in-safe storage with all my guns, and I have never had one of my guns rust inside a Bore-Store, even when I lived a stone’s throw from the ocean.

Bore-Stores are offered in a wide range of sizes, so you can find something to fit everything from a Snub-nosed revolver to a 32″-barrelled 50 BMG. Rifle-size Bore Stores can be purchased for $12.00 – $21.00 from Brownells. For long F-Class or tactical rifles, we recommend the 10″x52″ Scoped Shotgun Bag, Brownells item 132-000-003. You can also order direct from the Bore-Store manufacturer, Big Spring Enterprises, www.BoreStores.com. Big Spring will also craft custom sizes on request.

Consider Military-Style, Triple-Layer Bags for Long-Term Storage
While we prefer Bore-Stores for regularly-used guns, if you have heirloom firearms that will be kept in storage for very long periods without seeing any use, you may want to grease them up and place them in the thin, but rugged three-layer storage bags sold by Brownells. The bags are made from a three-layer laminate of polyester, aluminum, and polyethylene film, with a shiny silver exterior. Though the laminate is thin, the Brownells storage bags are puncture-resistant, and have a 0% moisture transmission rating so moisture can’t get inside. These bags are also resistant to petroleum-based chemicals and they won’t break down even in contact with soil or moisture.

3-layer Brownells storage bagHere’s one VITAL bit of advice for using these bags. Be absolutely sure, before you seal up the bags, that your guns are DRY and that all metal surfaces have been coated with an effective anti-corrosive, such as BoeShield T9 or Eezox. Brownells’ storage bags are inexpensive. A three-pak of 12″x 60″ rifle sacks (item 083-055-003WB) costs just $22.99 — under eight bucks a gun. That’s cheap insurance for rifles and shotguns that may cost thousands of dollars.

Get Your Guns Out of Foam-lined Cases — They Are Rust Magnets
Just about the worst thing you can do in the winter (short of leaving your rifle outside in the rain) is to store firearms in tight, foam-padded cases. The foam in these cases actually collects and retains moisture from the air, acting as the perfect breeding ground for rust.

Foam-lined hard caseRemember, those plastic-shelled cases with foam interiors are for transport, not for long-term storage. Don’t repeat the mistake of a wealthy gun collector I know. He stored four valuable Colt Single Action Army (SAA) revolvers in individual foam-padded cases, and locked these away in his gun safe. A year later, every one of his precious SAAs had rusted, some badly.

Permalink Gear Review, Tech Tip 9 Comments »
October 19th, 2014

How Altitude and Air Pressure Influence Ballistics

Suunto AltimeterOne of our readers asked “What effect does altitude have on the flight of a bullet?” The simplistic answer is that, at higher altitudes, the air is thinner (lower density), so there is less drag on the bullet. This means that the amount of bullet drop is less at any given flight distance from the muzzle. Since the force of gravity is essentially constant on the earth’s surface (for practical purposes), the bullet’s downward acceleration doesn’t change, but a bullet launched at a higher altitude is able to fly slightly farther (in the thinner air) for every increment of downward movement. Effectively, the bullet behaves as if it has a higher ballistic coefficient.

Forum member Milanuk explains that the key factor is not altitude, but rather air pressure. Milanuk writes:

“In basic terms, as your altitude increases, the density of the air the bullet must travel through decreases, thereby reducing the drag on the bullet. Generally, the higher the altitude, the less the bullet will drop. For example, I shoot at a couple ranges here in the Pacific Northwest. Both are at 1000′ ASL or less. I’ll need about 29-30 MOA to get from 100 yard to 1000 yards with a Berger 155gr VLD @ 2960fps. By contrast, in Raton, NM, located at 6600′ ASL, I’ll only need about 24-25 MOA to do the same. That’s a significant difference.

Note that it is the barometric pressure that really matters, not simply the nominal altitude. The barometric pressure will indicate the reduced pressure from a higher altitude, but it will also show you the pressure changes as a front moves in, etc. which can play havoc w/ your calculated come-ups. Most altimeters are simply barometers that read in feet instead of inches of mercury.”

As Milanuk states, it is NOT altitude per se, but the LOCAL barometric pressure (sometimes called “station pressure”) that is key. The two atmospheric conditions that most effect bullet flight are air temperature, and barometric pressure. Normally, humidity has a negligible effect.

It’s important to remember that the barometric pressure reported on the radio (or internet) may be stated as a sea level equivalency. So in Denver (at 6,000 feet amsl), if the local pressure is 24″, the radio will report the barometric pressure to be 30″. If you do high altitude shooting at long range, bring along a Kestral, or remember to mentally correct the radio station’s pressure, by 1″ per 1,000 feet.”

You can do your own experimental calculations using JBM Online Ballistics (free to use). Here is an extreme example, with two printouts (generated with Point Blank software), one showing bullet trajectory at sea level (0′ altitude) and one at 20,000 feet. For demonstration sake, we assigned a low 0.2 BC to the bullet, with a velocity of 3000 fps.

Trajectory of Bullet fired at Sea Level

Trajectory of Bullet fired at 20,000 feet

if you want to learn more about all aspects of External Ballistics, ExteriorBallistics.com provides a variety of useful resources. In particular, on that site, Section 3.1 of the Sierra Manual is reprinted, covering Effects of Altitude and Atmospheric Pressure on bullet flight.

Permalink Tech Tip 5 Comments »
October 17th, 2014

Online Barrel Weight Calculator from Pac-Nor

Can you guess what your next barrel will weigh? In many competition disciplines, “making weight” is a serious concern when putting together a new match rifle. A Light Varmint short-range Benchrest rifle cannot exceed 10.5 pounds including scope. An F-TR rifle is limited to 18 pounds, 2 oz. (8.25 kg) with bipod.

One of the heaviest items on most rifles is the barrel. If your barrel comes in much heavier than expected, it can boost the overall weight of the gun significantly. Then you may have to resort to cutting the barrel, or worse yet, re-barreling, to make weight for your class. In some cases, you can remove material from the stock to save weight, but if that’s not practical, the barrel will need to go on a diet. (As a last resort, you can try fitting a lighter scope.)

Is there a reliable way to predict, in advance, how much a finished barrel will weigh? The answer is “yes”. PAC-NOR Barreling of Brookings, Oregon has created a handy, web-based Barrel Weight Calculator. Just log on to Pac-Nor’s website and the calculator is free to use. Pac-Nor’s Barrel Weight Calculator is pretty sophisticated, with separate data fields for Shank Diameter, Barrel Length, Bore Diameter — even length and number of flutes. Punch in your numbers, and the Barrel Weight Calculator then automatically generates the weight for 16 different “standard” contours.

Calculator Handles Custom Contours
What about custom contours? Well the Pac-Nor Barrel Weight Calculator can handle those as well. The program allows input of eight different dimensional measurements taken along the barrel’s finished length, from breech to muzzle. You can use this “custom contour” feature when calculating the weight of another manufacturer’s barrel that doesn’t match any of Pac-Nor’s “standard” contours.

Smart Advice — Give Yourself Some Leeway
While Pac-Nor’s Barrel Weight Calculator is very precise (because barrel steel is quite uniform by volume), you will see some small variances in finished weight based on the final chambering process. The length of the threaded section (tenon) will vary from one action type to another. In addition, the size and shape of the chamber can make a difference in barrel weight, even with two barrels of the same nominal caliber. Even the type of crown can make a slight difference in overall weight. This means that the barrel your smith puts on your gun may end up slightly heavier or lighter than the Pac-Nor calculation. That’s not a fault of the program — it’s simply because the program isn’t set up to account for chamber volume or tenon length.

What does this mean? In practical terms — you should give yourself some “wiggle room” in your planned rifle build. Unless you’re able to shave weight from your stock, do NOT spec your gun at one or two ounces under max based on the Pac-Nor calculator output. That said, the Pac-Nor Barrel Weight Calculator is still a very helpful, important tool. When laying out the specs for a rifle in any weight-restricted class, you should always “run the numbers” through a weight calculator such as the one provided by Pac-Nor. This can avoid costly and frustrating problems down the road.

Caution: Same-Name Contours from Different Makers May Not be Exactly the Same
One final thing to remember when using the Barrel Weight Calculator is that not all “standard” contours are exactly the same, as produced by different barrel-makers. A Medium Palma contour from Pac-Nor may be slightly different dimensionally from a Krieger Medium Palma barrel. When using the Pac-Nor Barrel Weight Calculator to “spec out” the weight of a barrel from a different manufacturer, we recommend you get the exact dimensions from your barrel-maker. If these are different that Pac-Nor’s default dimensions, use the “custom contour” calculator fields to enter the true specs for your brand of barrel.

Credit Edlongrange for finding the Pac-Nor Calculator

Permalink Gunsmithing, Tech Tip 2 Comments »
October 13th, 2014

CUP vs. PSI — What’s The Difference in Pressure Measurements

by Philip Mahin, Sierra Bullets Ballistic Technician
This article first appeared in the Sierra Bullets Blog

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.

SAAMI CUP PSI Cartridge Copper Units Pressure PSI
Image by ModernArms, Creative Common License.

SAAMI CUP PSI Cartridge Copper Units Pressure PSICUP 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.

SAAMI CUP PSI Cartridge Copper Units Pressure PSI

Permalink Reloading, Tech Tip 1 Comment »
October 12th, 2014

Cartridge OAL — How It Affects Pressure, Velocity, and Accuracy

Berger Bullets COAL length cartridgeEffects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 1
by Bryan Litz for Berger Bullets.
Many shooters are not aware of the dramatic effects that bullet seating depth can have on the pressure and velocity generated by a rifle cartridge. Cartridge Overall Length (COAL) is also a variable that can be used to fine-tune accuracy. It’s also an important consideration for rifles that need to feed rounds through a magazine. In this article, we’ll explore the various effects of COAL, and what choices a shooter can make to maximize the effectiveness of their hand loads.

Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI)
Most loading manuals (including the Berger Manual), present loading data according to SAAMI (Sporting Arms and Ammunition Manufacturers’ Institute) standards. SAAMI provides max pressure, COAL and many other specifications for commercial cartridges so that rifle makers, ammo makers, and hand loaders can standardize their products so they all work together. As we’ll see later in this article, these SAAMI standards are in many cases outdated and can dramatically restrict the performance potential of a cartridge.

Bullet seating depth is an important variable in the accuracy equation. In many cases, the SAAMI specified COAL is shorter than what a hand loader wants to load their rounds to for accuracy purposes. In the case where a hand loader seats the bullets longer than SAAMI specified COAL, there are some internal ballistic effects that take place which are important to understand.

Effects of Seating Depth / COAL on Pressure and Velocity
The primary effect of loading a cartridge long is that it leaves more internal volume inside the cartridge. This extra internal volume has a well known effect; for a given powder charge, there will be less pressure and less velocity produced because of the extra empty space. Another way to look at this is you have to use more powder to achieve the same pressure and velocity when the bullet is seated out long. In fact, the extra powder you can add to a cartridge with the bullet seated long will allow you to achieve greater velocity at the same pressure than a cartridge with a bullet seated short.

Berger Bullets COAL length cartridge

Figure 1. When the bullet is seated farther out of the case, there is more volume available for powder. This enables the cartridge to generate higher muzzle velocity with the same pressure.

When you think about it, it makes good sense. After all, when you seat the bullet out longer and leave more internal case volume for powder, you’re effectively making the cartridge into a bigger cartridge by increasing the size of the combustion chamber. Figure 1 illustrates the extra volume that’s available for powder when the bullet is seated out long.

Before concluding that it’s a good idea to start seating your bullets longer than SAAMI spec length, there are a few things to consider.

Geometry of a Chamber Throat
The chamber in a rifle will have a certain throat length which will dictate how long a bullet can be loaded. The throat is the forward portion of the chamber that has no rifling. The portion of the bullet’s bearing surface that projects out of the case occupies the throat (see Figure 2).

Berger Bullets COAL length cartridge

The length of the throat determines how much of the bullet can stick out of the case. When a cartridge is chambered and the bullet encounters the beginning of the rifling, known as the lands, it’s met with hard resistance. This COAL marks the maximum length that a bullet can be seated. When a bullet is seated out to contact the lands, its initial forward motion during ignition is immediately resisted by an engraving force.

Seating a bullet against the lands causes pressures to be elevated noticeably higher than if the bullet were seated just a few thousandths of an inch off the lands.

A very common practice in precision reloading is to establish the COAL for a bullet that’s seated to touch the lands. This is a reference length that the hand loader works from when searching for the optimal seating depth for precision. Many times, the best seating depth is with the bullet touching or very near the lands. However, in some rifles, the best seating depth might be 0.100″ or more off the lands. This is simply a variable the hand loader uses to tune the precision of a rifle.

CLICK HERE to Read Full Article with More Info

Article sourced by EdLongrange. We welcome tips from readers.
Permalink Reloading, Tech Tip No Comments »
October 4th, 2014

Fascinating Test Shows Tuner Settings Can Alter Point of Impact

6PPC Pascal Fischbach Bukys Barrel Tuner sine waveHave a good look at the photos below — this may be one of the most noteworthy target strings we’ve ever published. What you can see is the effect of barrel tuner position on point of impact (POI). You can clearly see that the tuner position alters the up/down POI location in a predictable fashion.

This remarkable 15-shot sequence was shot by French benchrester Pascal Fischbach using his 6 PPC fitted with a CG (Carlito Gonzales) action and a Bukys barrel tuner.

Pascal reports: “After [bullet] seating and load validation, I put the Bukys tuner on, screwing it out 10 turns. According to Carlito, the CG’s super stiff action-to-barrel fit gives a faster vibration modulus that is detrimental below 10 turns [position of the tuner].” Pascal’s procedure was to screw out the tuner 1/4 turn progressively from one shot to the next. He shot one bullet at each tuner position, with a total of 15 shots.

15-Shot Sequence with Tuner Changes
6PPC Pascal Fischbach Bukys Barrel Tuner sine wave
CLICK HERE to SEE Large Version of Complete Test Strip (All 15 shots in a row).

Left Half of Target Strip (shots with 1/4 rotation change of tuner in sequence)
6PPC Pascal Fischbach Bukys Barrel Tuner sine wave

Right Half of Target Strip (shots with 1/4 rotation change of tuner in sequence)
6PPC Pascal Fischbach Bukys Barrel Tuner sine wave

Pascal observed: “Note the point of impact displacement [from shot to shot] tracks clearly along a sinusoide (sine wave curve).” This is indeed notable and significant! This shows how the tuner’s ability to change barrel harmonics can alter the position of the muzzle as each bullet exits, resulting in a higher or lower POI. Pascal sent his results to Carlito Gonzales in Argentina for analysis.

Pascal poses this question to readers: “Guess which three positions Carlito recommends to try?”

Editor’s Note: While this target sequence clearly shows how tuner position can alter bullet point of impact, this, by itself, does not tell us which tuner position(s) are best for accuracy. That will require further multi-shot group testing, involving careful experimentation with tuner position (and powder charge weights). But for those folks who doubt that a tuner can make a difference on a short, fat barrel, just take another look at the photos. The up/down changes are undeniable, and noteworthy in the wave pattern they follow.

6PPC Pascal Fischbach Bukys Barrel Tuner sine wave

Permalink Bullets, Brass, Ammo, Gunsmithing, Tech Tip 6 Comments »
October 2nd, 2014

How to Build Your Own Concrete Shooting Bench

Who hasn’t dreamed of having a professional-quality permanent shooting bench on their own property? Well here’s an article that can help you make that dream come true. The latest online edition of RifleShooter Magazine shows how to build a quality concrete shooting bench step-by-step.

build your own concrete shooting bench

All aspects of the construction process are illustrated and explained. The author, Keith Wood explains: “Construction happened in three phases — first creating the slab foundation, then the support pillars (legs), and finally the table.”

Click image below to load article with slide show.
build your own concrete shooting bench

Each step in the process is illustrated with a large photo and descriptive paragraph. Starting with framing the foundation (Step 1), the article illustrates and explains the 15 Steps that produce the finished, all-concrete bench, shown below.

build your own concrete shooting bench

Permalink Tech Tip No Comments »
September 29th, 2014

You Can’t Shoot What You Can’t See

“All dressed up and nowhere to go” was the comment our IT guy, Jay Christopherson, sent with this photo. This is Jay’s testing set-up at his home range, complete with PVM-21 chronograph and wireless target-cam. The camera signal is sent, via WiFi, to Jay’s laptop computer. However, even with all that high-tech electronic gear, you can’t make the shot if you can’t see the target through the rifle-scope. On this morning, heavy ground fog completely obscured the target. Jay told us: “I ended up waiting a little over an hour for the fog to burn off enough so that I could see the 600-yard target. What was funny was that I had a perfectly clear picture of the target via the target-cam and monitor. But there was no way to aim the rifle since the riflescope showed nothing but fog.”

PVM-21 Target Cam Camera Labradar Video Fog F-class Washington Jay

This photo was taken by Jay at the Cascade Shooting Facility in Ravensdale, WA. The rifle is Jay’s .284 Shehane F-Class rifle. Jay was testing primers for Extreme Spread (ES) variation around 9:00 am. Nature was not cooperating. Jay was running Hodgdon H4831sc and testing various primers to see which provided the best numbers.

The chronograph is the Kurzzheit PVM-21. Equipped with infrared sensors, the PVM-21 is our “go-to” chron for most velocity testing, with an Oehler 35P for “back-up”. The PVM-21 (now updated with Kurzzheit’s BMC-19 model) sets up quickly and gives reliable results in any light conditions. But there is something even more sophisticated on the horizon — the new Labradar, a “stand-off” chronograph that uses Doppler radar to measure bullet speed.

PVM-21 Target Cam Camera Labradar Video Fog F-class Washington Jay

Jay explains: “I am (somewhat) patiently waiting for the new Labradar to release. The PVM-21 works pretty well most of the time and is easy to setup. I do get odd readings out of it every so often, but they are pretty obvious when they occur.” The advantage of the Labradar (if it ever comes to market) is that the unit sits to the left or right of the rifle. The Labradar is situated out of the bullet path, so there is no chance of shooting the chronograph by accident. Another advantage of the Labradar is that you can set it up without needing to go forward of the firing line, which would require a safety break.

Permalink Gear Review, Tech Tip 4 Comments »
September 28th, 2014

Tech Tip: Coping with Corrosive Ammo

corrosive ammunition ammo BrownellsNo 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.

AK-74 after firing corrosive ammo and not being cleaned for a week.
Corrosive Ammo ammunition
Image courtesy ADCOFirearms.com.

Video Tip from EdLongrange. We welcome reader submissions.
Permalink Tech Tip No Comments »
September 28th, 2014

Find and Download MIL-STD Spec Sheets for FREE

Looking for authentic U.S. Military Specification Standards (MIL-STD) for gun parts, safety products, or other hardware? Log on to EverySpec.com. This website provides FREE access to the complete archive of U.S. Government spec sheets and technical manuals. You can quickly access and download thousands of public domain U.S. Government documents. For example, we searched for “Picatinny” and came up with MIL-STD-1913 “Dimensioning of Accessory Mounting Rail for Small Arms Weapons”. With one click we downloaded the file as a PDF. Then a search for “M118″ yielded the engineering drawing for 7.62×51 M118 LR Match ammo. Pretty cool.

Using EverySpec.com is fast and easy. And everything you find and save is FREE. Search as often as you like — there are no limits on search requests or downloads. You can either search by keyword, or Federal Supply Class Code (FSC). CLICK HERE for a complete list of FSCs for all products.

Here are FSCs for a few common product types. Keep in mind that there are hundreds of other FSCs — for everything from Office Supplies (FSC 7510) to Nuclear Projectiles (FSC 1110).

1095 — Miscellaneous Weapons (incl. Knives)
1240 — Optical Sighting and Ranging Equipment
1395 — Miscellaneous Ammunition (incl. Small Arms)
3455 — Cutting Tools for Machine Tools
6140 — Batteries, Rechargeable
6230 — Electric Portable Lighting Equipment
7640 — Maps, Atlases, Charts and Globes
8340 — Tents and Tarpaulins
8405 — Outerwear, Mens

Credit Gunsmith Thomas ‘Speedy’ Gonzales for finding this resource. Thanks Speedy!
Permalink Bullets, Brass, Ammo, Tech Tip 1 Comment »
September 24th, 2014

Eye Protection — LuckyGunner Labs Field Tests

If you’re one of those folks who doesn’t wear eye protection, you need to check out the LuckyGunner Labs Eye Protection Test. For those who DO wear safety glasses — don’t assume that everything is OK. Just because you purchased name-brand “safety glasses” doesn’t mean that you are getting truly effective protection. In fact, many forms of protective eyewear sold today are flimsy, or poorly made. Consequently, they won’t stop even low-energy, slow-velocity fragments.

CLICK HERE to Read Complete Eyewear Test Report by LuckyGunner Labs.

Lucky gunner eyewear testTwo years ago, LuckyGunner Labs conducted very extensive field tests of 28 types of eyewear, ranging in price from $7 to $220. Remarkably, some of the most expensive safety eyewear performed no better than $10 items. Many of the products failed shockingly — with the lenses coming right out of the frames when hit with pellets. LuckyGunner recorded these kind of failures even with ANSI Z87-”approved” eyewear. The reason is that the Z87 test is not tough enough: “The basic ANSI standard is referred to as Z87, and you’ll see this marked in a number of locations on most eye protection marketed to shooters. However, the Z87 impact standard involves a .25″ steel ball traveling at 150 fps — this is fine for protecting eyes from debris that might fall or be thrown, but is not extremely relevant to shooters, who are dealing with objects traveling at much higher velocities.”

Standard Impact speed Caliber/Size
ANSI Z87.1-2003
High Velocity
150 feet/second
45 meters/second
0.25″ diameter steel ball
(25 caliber)
Mil-PRF-31013
Vo ballistic test
640-660 feet/second
195 meters/second
0.15 inch diameter steel projectile (15 caliber)

The testers recommend you select eyewear that meets military specification (above and beyond ANSI Z87). The MIL-PRF-31013 Standard covers projectiles up to 650 feet per second. This is much more stringent. Additionally, you want to replace often-used protective eyewear every year or so. Long-term exposure to UV radiation can weaken polycarbonate and lessen its ability to withstand impacts.

SUMMARY — What to Look for in Protective Eyewear

THE GOOD — Eyewear Protects Against Direct Hit with .22 Short Bullet
APEL Revision Sawfly eyewear was shot with a .22 Short, pushing a 29 grain bullet at 710 fps. That’s not powerful by modern firearm standards, but this might be fairly representative of a ricochet bullet fragment. The Sawfly lens stopped this 29gr bullet with minimal damage to the cheek area.


Lucky gunner eyewear test
THE BAD — Remington Eyewear Lenses Separate. Right Lens Enters Eye Socket
The most gruesome example was the cheap Remington eyewear which shed both lenses back towards the eyes, one of which embedded itself into the eye socket. The real-world implications of this action are disturbing to say the least.


Lucky gunner eyewear test

THE UGLY — Prescription Glasses Failed Miserably
Many ranges don’t see any need for protective eyewear beyond prescription glasses. However, most prescription lenses offer little if any protection. If the prescription lenses are glass, this can create more problems. As shown below, these prescription glasses offered no ballistic protection, and, in fact, proved more dangerous to the eyes due to the flying glass shards.

Lucky gunner eyewear test

_blank
Results Chart, Video Clips, and Photos copyright Luckygunner.com.

Summary and Conclusions:
For faster-moving projectiles such as ricochet fragments, you need high quality, tested eye protection. LuckyGunner recommends eyewear with a single (one-piece) lens for any activity where your face might be struck by small, fast-moving objects. Individual lenses detach from the frames once a certain level of force is reached, and they are driven back into the eye sockets, where considerable damage may be done. There are good examples of protective eyewear with two separate lenses, but a broad, one-piece lens distributes force much better.

Lucky gunner eyewear testA wide, comfortable, and preferably soft rubber nosepiece is critical. Along with good “arms”, this will serve to keep the eye protection in place and will also reduce the chances of the lens being driven down or back into the face with enough force to damage the orbital bones.

A frame that connects across the top of the lens, not individual arms which attach to the outside corners of the lens, is recommended. This will reduce the chances of the lens detaching from the frame under impact (it’s still possible, just less likely). Some types of eye protection actually use the frame to absorb impact and distribute force.

NOTE: Andrew, the author of the LuckyGunner Eyewear report, was a former Navy Corpsman. Accordingly, he is familiar with health and safety matters.

Permalink - Videos, Tech Tip 3 Comments »