Shallow primer pocket

[Mandoair]

Boolit Mold
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Apr 2021
Location
Alaska
Posts
16
I ran into something new yesterday. Mixed 10mm range brass that I have been shooting for some time. I never noticed a problem before but the primers just won’t go below the face. I have been using a rock chuker and Hornady dies. The pockets are measuring around .117 to .120. Pockets are clean enough. Went out and got a uniformer and went to hogging out to .121 or so. I have used these cases 4 or 5 times now. Anyway trying to figure out why the pockets are so shallow. Is it normal ware and tear? Been using cci 350s but light loads. We use what we have Yes❓ I am new to this kind of work. Thanks

[Winger Ed.]

With hot loads and after several re-loadings, I've had primer pockets get loose- as in the diameter 'grows'.
But not get shallower.

If the brass is all of one brand or head stamp, they may have been made that shallow for whatever primers the factory used.
If the bottom/corner edges of the pockets are good & clean, and free of crud & soot, that's a bit of a headscratcher.

[MostlyLeverGuns]

It is not uncommon for primer pockets to get more shallow under higher pressure with multiple reloads. The bench rest folks have mentioned this and redoing primer pocket uniforming when it does occur for many years.

[kevin c]

That’s something I didn’t know. It figures the detail oriented benchrest crowd would know something like this.

[mdi]

Yer not stuffing Large Rifle Primers in the cases, are ya? I don't have a 10mm to reload but I have reloaded many other high pressure cartridges and can't remember any "shallow primer pockets". I have some Federal 44 Magnum nickel plated brass I've used exclusively for my "T-Rex Killer" loads; max loads of WC820 under a 265 gr RNFP. So far I have 10-12 reloadings with no noticable changes (don't clean primer pockets either)...

[zarrinvz24]

I'm not sure if you've considered this possibility, but on high pressure cartridges, the primer pocket bottom tends to get lower and lower the more use the brass experiences. Higher pressures increase this effect. I've not personally observed this phenomenon in pistol cases, however I've see it in 30-06 (hot loads in the thick military brass), and I've seen it in a friends 30-30 fired from a contender, and they were past maximum loads. My solution, primer pocket reamer.

[Mandoair]

As for high pressure ❓ I am using lp mag primers out of necessity for lack of lp. But loading down to bearly above the low end of the data. As for using lr primers I won’t dignify that with an answer. I have been using the uniformer with great results. Thanks

[zarrinvz24]

That’s good to hear that you’ve been able to work through it. I’ve found with some brass of forum manufacture, the pocket depth is more shallow than spec. I’ve always assumed this was caused by mm to imperial unit conversion. Irregardless, primer uniformity sure takes a lot of frustration out of the process. FWIW, I use SRP exclusively for all small primers. Just work up your loads from minimum.

[Mandoair]

Thanks I just ran out of spp and have come into 3000 srp so yes me too.

[Dieselhorses]

https://castboolits.gunloads.com/sho...Primer-Pockets

[Philien]

Another item to check is your decapping rod.
If set to deep it can push the web down.