How to Remove Primer Pocket Crimps from Fired Brass
The U.S. Army Marksmanship Unit (USAMU) regularly releases a reloading “how-to” article on the USAMU Facebook page. Here’s a helpful USAMU guide on removing military primer pocket crimps. If you ever use surplus military brass, you really should this article. It contains vital information “learned the hard way”. The writer has tried many different options for removing/swaging out crimps. He weighs the pros and cons of various methods and provides some advice that will save you time and headaches. This article was the second in a 3-part series. Visit the USAMU Facebook page regularly for other informative articles on reloading methods.
A common question, and important issue with US GI surplus 5.56 brass is “what to do with the primer crimp?” Our Handloading Shop does not prime/re-prime GI 5.56 brass, as we receive it in virgin state (primed) and don’t reload it. However, our staff has extensive private experience handloading GI brass in our own competitive shooting careers, and have several tips to offer.
Once the brass is full-length sized and decapped, the staked-in ring of displaced metal from the primer crimp remains, and hinders re-priming. Some swaging tools exist to swage out this ring, allowing free access to the primer pocket. Some are stand-alone products, and some are reloading-press mounted. Early in this writer’s High Power career, he used the common press-mounted kit several times, with less than stellar results.
Setting Up Swaging Tools
Surplus brass tends to come from mixed lots, and primer crimp varies from very mild to strong. Also, primer pocket dimensions vary. So, setting up this “one size fits most” tool involves trying to find a happy medium for a selection of different types of brass in your particular lot. Some are over-swaged, some under-swaged, and some are “Just Right.” Overall, it was a time-consuming and sub-optimal process, in this writer’s experience.
Cutting Out the Crimp Ring with a Chamfer Tool
[After trying swaging tools] this writer evolved to using the ubiquitous Wilson/RCBS/Other brands chamfer and deburring tool to cut out only the displaced crimp ring at the top of the primer pocket. One caution: DON’T OVER-DO IT! Just a little practice will let the handloader develop a “feel” for the right degree of chamfer that permits easy re-priming without removing so much metal that primer edges start to flow under pressure. For this writer, it was three half-turns of the tool in the primer pocket, with medium pressure.
Here, as with all bulk reloading operations, mechanization is our friend. A popular reloading supply house has developed an inexpensive adaptor that houses the chamfer/deburr tool (retained by an allen screw) and allows mounting in a hand drill or drill press. This speeds the operation significantly, as does use of one of the popular Case Preparation Stations that feature multiple powered operations. (Say good-bye to carpal tunnel syndrome and arthritis!)
One advantage of chamfering the primer pockets lightly to remove remnants of primer crimp, vs. swaging, is that primer pockets are not loosened in this process. US GI (usually LC) NATO 5.56 brass has a great reputation for longevity due to the superior hardness of the case head vs. some softer brands of commercial brass. This means the brass will stand up well to multiple full-pressure loads without loosening primer pockets, and the chamfering method helps support this benefit.
Powered Case Prep Centers — What to Look For
A word of advice (often learned the hard way) — think carefully before jumping on the “latest/greatest” case prep center. One with a proven, long-time track record of durability and excellent customer support has a lot going for it, vs. the flashy “new kid on the block.” Analyze the functions each case prep center can support simultaneously — i.e., can it chamfer, deburr and clean primer pockets all at the same time, without having to re-configure?Do the tool-heads that come with it look truly functional and durable? If not, can they be easily replaced with proven or more-needed versions, such as a VLD chamfer tool, or a solid/textured primer pocket cleaner rather than a less-durable wire-brush type?
Tips for Priming with Progressive Presses
When re-priming, a couple of factors are worth noting. When re-priming using either single-stage presses, hand tools, or bench-mounted tools (such as the RCBS bench-mounted priming tool), precise alignment of the primer pocket entrance with the primer is easily achieved, and priming goes very smoothly. When using certain progressive presses, due to the tolerances involved in shell-heads, etc., one may occasionally encounter a primer that isn’t quite perfectly aligned with the primer pocket.
If resistance is felt when attempting to re-prime, DO NOT attempt to force the primer in — doing so can be dangerous! Rather, just exert SLIGHT upward pressure to keep the primer in contact with the case-head, and with the support hand, move the case back/forth a trifle. The primer will drop into alignment with the primer pocket, and then prime as usual. After priming, check each seated primer by feel. Ensure it is below flush with the case head (cleaning primer pockets helps here), and that there are no snags, burrs or deformed primers.
More Info on Primer Pocket Swaging
For more information about removing military crimps in primer pockets, we recommend you read Get the Crimp Out on the Squibloads Gun Thoughts Blog. This is a detailed, well-illustrated article that shows how to use various primer pocket reamers/cutters. It also has a very extensive discussion of swaging using CH4D, RCBS, and Dillon tools. The Squibloads author had much better luck with swaging tools than did the USAMU’s writer — so if you are considering swaging, definitely read the Squibloads article.
The illustration of primer pocket types is from the Squibloads Blog Article, Get the Crimp Out.
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Tags: CH4D, Military Crimp, Primer Pocket, Squibloads, Staked Primers, Swage Tool, Swaging, USAMU
Nice artical. I have the Dillon tool witch is fast and works well. Actually its for sale, hopefully my crimp removing days are over
Primer Pocket Crimp Removal for Small Pistol Primers
I think everybody including the manufactures’ have way over thought removing crimps. The idea of using a countersink to bevel the top edge of the primer pocket is effective at removing the crimp but the downside is the lack of control over the depth. The advantage is that beveling does significantly help to reduce or near eliminate flipped primers during priming. The ideal solution is to: 1) lightly bevel the primer pocket to remove the crimp and aid in smoother primer centering and seating 2) have depth control so no excessive material is removed and brass previously processed this way is not affected 3) the sidewall of the primer pocket other than the bevel area is not affected 4) the method is very cost effective and 5) the process is simple and fast.
This is my solution for small pistol primers only. Works best in a drill press.
1) purchase the long narrow step drill bit that ranges in size from 1/8 to 1/2. (Harbor Freight 91616)
2) the only 2 sizes to be concerned with are: 5/32 and 3/16. 1/8 will be ground off.
5/32 is smaller than the primer diameter- it is the pilot and depth gauge. 3/16 step will create the bevel
3) If you can cut a 9mm case in to a cross section this will be very helpful in setting the depth. The average depth of a primer pocket is about 0.120”. If you cannot cut a cross section of a case then slightly drill out the flash hole so you can better see the bottom of the step bit when inserted.
4) The idea here is to grind the 5/32 portion of the step drill so that: 1) the face is flat so not cut the primer pocket when bottomed out and 2) to grind off just enough to get the bevel portion of the 3/16 step to just trim the face rim of the casing removing the crimp and putting a very narrow bevel on the leading edge of the primer pocket.
This is a trial and error at this stage so do not get aggressive with grinding the 5/32 portion. Trim just enough of the 5/32 at this point to get the 3/16 bevel to approach the crimped area. Chuck the bit and test on a casing. Grind a tad off and chuck again. Keep doing so until the bevel is lightly cut. Using an old primer test the how the primer inserts and grind again as necessary. There should be a narrow bevel ring at top of the primer pocket mouth much like cutting a valve seat. It should be the same width as the bevel on the step bit and NOT recessed into the casing.
Tip: If you grind this on a grinding wheel like I did you never get a totally flat face on the bit. So when fine tuning the depth, rotate the bit and find the high edge and lightly touch that against the stone to adjust the depth. This method will produce no marks in the bottom of the primer pocket.
Analyzing the situation: 10-20 minutes
Making the bit: less than 10 minutes
Processing brass: 2-3 seconds in a drill press. Press brass straight up into the bit. You can hold the brass in your hands but I prefer to wear mechanic gloves. Adjust drill press table height to make it a comfortable hand rest.
My bit is designed for 9mm brass because that is all I shoot. All small primers are essentially the same dimensions. I would not go as far as to say that all small primer shell casings have the same depth so you may have to make additional bits for other calibers. The worst case stamps with crimps I have found so far for 9mm are SAR and WIN. These guys always gave me primer issues in the past …. But no more!!! I process all my brass with this method.
Thanks and enjoy
Mike K