Primers/Primer pocket dimensions lesson

IAyoteHNTR

IAyoteHNTR

New member
I've been prepping and loading a bunch of WIN .223 brass for my 6X45 and noticed rather quickly that every piece of once fired WIN brass I have needed the primer pocket uniformed as they were too shallow. That got me to wondering about the specs on dimensions concerning primers and primer pockets and after a few Google searches I had my questions answered but I thought I would share what I've been experiencing and doing.

After getting the information I was looking for I started measuring some of the primers I have. I measured 5 CCI 400 small rifle primers and found them to be from .120" to almost .121" and I then measured 5 WSR primers and they were from .119" to .120"

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And since I was removing a decent amount of brass from the WIN .223 brass out of the primer pockets I measured several of the cases primer pockets for depth before and after running them through my RCBS prep station where I have a small primer pocket uniforming attachment fit on to it. The primer pockets were measuring from .115" to about .117" on average before I ran them on the uniforming bit. After they were measuring right at .120". Here's the material that I cut out of the primer pockets out of just 25 pieces of brass.

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I found some dimension specs from Sinclair Intl's Precision Reloading & Shooting Handbook, 10th Edition.........

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So I found this information and my personal experience the last few days to be a nice lesson and thought it might be worthwhile posting about it for others.
 
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I'm about to start prepping a bunch of R-P .223 brass. It will be interesting to see how the primer pockets in that brass compares to the WIN.
 
I just finished fully prepping/priming 50 pcs of once fired R-P .223 brass to load up some .223 rounds with and the primer pockets in them were much closer to spec. I didn't have to cut very much material out of them to get them all uniformed and I also noticed the R-P brass is definitely softer than the WIN brass, the brass cut out of the pockets much easier. Here's the brass shavings from 50 pcs of the R-P brass, which is about 1/2 the shavings I got from just 25 pcs of WIN brass.
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When I first got my RCBS Trim Mate Case Prep Center I uniformed the primer pockets on a bunch of brass with large rifle primer pockets.

When I started seating primers into the brass the primers were seating without much pressure at all. The uniforming tool I had was a tad bit too big in diameter and I made a bunch of good and new brass pretty much worthless.

Some of the primers were so loose in the pockets they moved around in and out when I shook the brass.

Before I got the RCBS Case Prep Center I never uniformed any primer pockets and I had never had any problems with my primer pockets.

I remember some one on this forum giving a warning about removing brass from the primer pockets. In his opinion he thought that you may wish after reloading the brass a few times that you had not removed any brass from the primer pocket area.
 
I would think it would be pretty easy to wreck good brass. Just a "hot" load itself will do enough damage to pockets. Never seen a need for uniforming pockets in a hunting rig.
 
Originally Posted By: Tim NeitzkeI would think it would be pretty easy to wreck good brass. Just a "hot" load itself will do enough damage to pockets. Never seen a need for uniforming pockets in a hunting rig.

I agree on all accounts.
 
I was just having a conversation with my dad about this earlier in the morning (he is an old time reloader and has been doing it his whole life). I was thinking about getting a prep station. He was saying the same thing as the above post. If you keep removing the brass from the primer pocket he believes you are just shortening the life of the case.
 
Originally Posted By: Big-BobI was just having a conversation with my dad about this earlier in the morning (he is an old time reloader and has been doing it his whole life). I was thinking about getting a prep station. He was saying the same thing as the above post. If you keep removing the brass from the primer pocket he believes you are just shortening the life of the case.

The RCBS Trim Mate is a great tool! I just don't uniform primer pockets with it any more.
 
I'm just uniforming the pockets this one time and they should be good from here on out. The WIN brass I could hardly get primers into before I uniformed them. I guess I don't see the harm in it at all.

I got to thinking about how much brass I have prepped in the last year. I have done about 250 6BR cases and I didn't need to uniform the small primer pockets in that Lapua brass, they were already near perfect. I did about 300-350 .243 cases and almost all if it was once fired when I got it and it was all WIN and R-P brass and when I uniformed those large primer pockets I didn't get hardly any brass shavings out of them at all and I reloaded and shot some of that brass 3-4 times and never had an issue with a primer pocket getting big or loose and I had some fairly hot loads.

I think the .223 WIN brass that I got recently must have come from a batch where the primer pockets were just manufactured on the shallow side. I have primed about 100 cases of that brass so far and there is a nice resistance while putting in the primers but I don't have to "force" them in like I would have had to if I hadn't uniformed the pockets. I'll get a few firings on some of that brass and see how things go but I highly doubt I'll have any issues. I could see having problems if you had a cutting tool that was not the right dimensions/specs but from my measurements I'm getting after I uniform the pockets they are near perfect right in the middle of the suggested range for the dimensions that were shown in the picture above.
 
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I measured the diameter of the cutting bit I'm using and it measures right @ 1.730" which according to the published info is the minimum for the diameter of small primer pockets and when I was measuring the depth of the primer pockets I uniformed I was getting just about exactly .120" depth.

Some of you guys made me nervous about uniforming the pockets and I know I don't have near the experience some of you do so I also measured several of the WIN cases inside diameter of the primer pockets and they measured from .171" to .172" and the WSR and CCI primers all measured right at .175" so that's where the light resistance is coming from when I'm putting in the primers, I'm putting something .175" wide into a .171"/.172" hole. I just got back from shooting some test loads I loaded up for my .223 using some of the R-P brass that I prepped so I quickly FL resized/deprimed 5 of those cases and measured the inside of the primer pockets just to see if they "grew" at all and they did not. They are the exact same dimensions I am getting on the brass that I have prepped but not shot yet so I think all is well.
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But thank you for your opinions and expertise guys. I'm here to learn and hopefully someone out there is learning right along with me.
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