January 9th, 2019

Loading Accurate Pistol Ammo for Competition — USAMU Tips

Accurate Reloading hand loading handgun pistol progressive 9mm .45 ACP
Photo courtesy UltimateReloader.com.

The U.S. Army Marksmanship Unit (USAMU) regularly publishes a weekly reloading article on its Facebook Page. In this article, the second in a 3-part series, the USAMU covers the process of loading competition pistol ammunition. The authors focus on two key elements — the taper crimp and the quality/uniformity of the original brass. If you shoot pistol competitively, or just want to maximize the accuracy of your handguns, read this article. The taper crimp tips are very important.

Pistol Reloading USAMU taper crimp Brass

Loading Accurate Competition Pistol Ammunition — Part 2 of 3

Today, we resume our series on factors affecting accuracy in pistol handloads. Readers who missed Part One can visit our USAMU Facebook Page. Scroll down to March 28, 2018 to find that first installment which is worth reading.

One often-overlooked aspect of handloading highly-accurate pistol ammunition is the amount of taper crimp used, and its effect on accuracy. (NOTE: this article pertains to loading for semi-autos – revolver crimp techniques involve some quite different issues.) Briefly, different amounts of taper crimp are used with various handloads to obtain best accuracy. The amount is based on bullet weight, powder burn rate and charge, plus other factors such as case neck tension. During machine-rest testing of experimental Service Pistol ammunition, many variables are examined. Among these, our Shop often varies a load’s crimp in degrees of 0.001″ when re-testing for finest accuracy.

How to Measure Taper Crimp on Pistol Cartridges
One question that often arises is, “How do I measure the taper crimp I’m putting on my cartridges?” Using the narrow part of one’s dial caliper jaws, carefully measure the case diameter at the exact edge of the case mouth on a loaded cartridge. It’s important to take several measurements to ensure consistency. Also, be sure to measure at several places around the case mouth, as case wall thickness can vary. After measuring 2-3 cartridges with a given crimp setting, one can be confident of the true dimension and that it can be repeated later, if needed.

Accurate Reloading hand loading handgun pistol progressive 9mm .45 ACP

However, for good results, one must use brass from one maker due to variances in case wall thickness. For example, the same degree of crimp that imparts a measurement of 0.471″ with Brand X brass may result in 0.469″ with Brand Y. Thus, for best accuracy, using brass from the same manufacturer is important — particularly for 50-yard Slow Fire. In a perfect world, it is better still to use brass from one lot number if possible. With the popularity of progressive presses using interchangeable tool heads, keeping separate tool heads adjusted for each load helps maximize uniformity between ammunition lots.

Brass Uniformity and Accuracy
Brass is important to pistol accuracy. While accurate ammunition can be loaded using brass of mixed parentage, that is not conducive to finest results, particularly at 50 yards. It is important for the serious competitor to pay attention to his brass – even if only for the 50-yard “Slow Fire” portions of “Bullseye” matches and practice. By segregating brass as described above, and additionally keeping track of the number of times a given batch of cases has been fired, one can ensure case neck tension and case length are at their most uniform.

Accurate Reloading hand loading handgun pistol progressive 9mm .45 ACP

Given the large volumes of ammunition consumed by active pistol competitors, using inexpensive, mixed surplus brass for practice, particularly at the “short line” (25 yards), is understandable. In NRA Outdoor Pistol (“Bullseye”), the 10-ring is relatively generous — especially for a well-trained shooter with an accurate pistol and load. However, for the “long line” (50 yards), purchasing and segregating a lot of high-quality brass to be used strictly for slow-fire is a wise idea. To keep track of your brass on the line, use a unique headstamp marking with 1 or 2 colors of marking pen ink.

Uniform Cartridge Overall Length is Important
Cartridge case Overall Length (OAL) uniformity as it comes from the factory is important to achieving utmost accuracy. More uniform case lengths (best measured after sizing) contribute to greater consistency of crimp, neck tension, ignition/burn of powder charge, headspace (rimless cartridges), etc. Cartridge case-length consistency varies noticeably by maker and, with lesser manufacturers, also from lot to lot. Some manufacturers are more consistent in their dimensions than others, and also in the hardness/ductility of their brass. Similarly, pay attention to primer brands, powder lot numbers, etc.

This concludes Part 2 of our series – Part 3 will be upcoming soon. Stay safe, and good shooting!

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June 11th, 2015

Precision Handloading for Pistols — Tips from the USAMU

USAMU Service Pistol Handgun Tip Advice Reloading

This week, the U.S. Army Marksmanship Unit is pleased to host pistol teams from the various U.S. Armed Services in the 56th Annual Interservice Pistol Championship. Our Handloading Shop members have enjoyed discussing pistol accuracy and enjoying the camaraderie of competitive shooters from all over. In that spirit, this week’s topic will focus on handloading for best pistol accuracy, rather than our usual rifle-oriented information.

Optimize the Taper Crimp
One often-overlooked aspect of handloading highly-accurate pistol ammunition is the amount of crimp and its effect on accuracy. Different amounts of taper crimp are used with various handloads to obtain best accuracy. The amount is based on bullet weight, powder burn rate and charge, plus other factors. It is not unusual for our Shop to vary a load’s crimp in degrees of 0.001″ and re-test for finest accuracy.

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January 12th, 2014

Redding Micro-Adjust Taper Crimp Dies for .223 Rem and .308 Win

Redding Rifle .223 Rem .308 Win taper crimp micrometer dieRedding is now offering Micro-Adjusting Taper Crimp Dies for the .223 Remington (5.56×45) and .308 Winchester (7.62×51), the two most popular cartridges used in competitive rifle shooting. New for 2014, these top-adjusting, micrometer-style dies, you can adjust crimp precisely without having to back-out the die and reposition the lock ring.

The process of traditional taper crimp die adjustment is generally both time consuming and imprecise due to the 1:14″ thread pitch coupled with the need to reposition the lock ring after each adjustment. The new Redding Micro-Adjusting Taper Crimp Dies for .223 Rem and .308 Win use a knurled, micrometer-type head situated to provide approximately +/- 0.100″ of adjustment after initial die set-up. The actual crimp is applied with a hardened steel “free floating” internal sleeve.

To Taper Crimp or Not to Crimp?
That Depends…

Do you actually need a taper crimp on .223 Rem or .308 Win cartridges? If you are shooting a precision bolt gun, the answer is “probably not”. However, if you are hand-loading ammo for a semi-automatic rifle, there are reasons you may want to apply a taper crimp on the cartridge. And high-volume .223 Rem shooters may want to apply a taper crimp, particularly when loading mixed headstamp brass using a progressive press. The new Redding dies allow you to control the amount of crimp easily and more efficiently. Redding claims that: “Down time and loss of production due to adjustment of the crimp are virtually eliminated, dramatically increasing the rounds per hour rates of all progressive and turret-style presses.”

High-volume hand-loaders often struggle with the realities of case variation and the resulting difficulties in obtaining a uniform crimp. Redding notes: “Case length is not the only variable, as case neck-wall thickness also impacts where the case intersects the die’s tapered crimping surface.”

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