What can cause primers to be a little proud after firing?

I've checked the headspace, using the RCBS mic kit, and the cases show a chamber about .001 longer than a go gauge.

Not a hot load, no cratering, and not even sharp edges on the primers?

TIA,

flaco

How many times have your cases been reloaded? Could be expanded primer pockets. Primers could be expanding trying to seal off the gas as they are fired.

I've gotten proud primers in low pressure loads. Case moves forward and not enough pressure to move the head back but enought to move the primer.

Hello,
As someone else mentioned, how many firings with your brass?? Federal brass is known to have soft primer pockets even as new, but same problem will crop up w/ over used brass of other mfg. as well.

it could be not enough pressure. brothers 25-06 did it on most loads he worked up. eventually you get enough pressure in there that the appear to stay put. i could go into more depth but i dont think its needed

I concur with those who believe low pressure is the culprit. I've shot loads with Federal brass extensively and even if the primers are a little loose the primers aren't "proud" (reminds me of the ancient term "proud flesh") when fired with loads of normal working pressure.

If you want to see proud primers, put rubber bullets in 44 Mag. cases with primers only and no powder. The primers will be very proud unless you drill out the flash holes to a larger size.

Cartridge is 7x57, Remington case, 45 gr. IMR 4350, 139gr. Hornady.

This load is right in the middle of loads suggested in my Lyman book.

(Although perhaps a little low in comparison to loads chosen by AR members. LOL.)

Any further comments?

flaco

quote:

Cartridge is 7x57, Remington case, 45 gr. IMR 4350, 139gr. Hornady.

This load is right in the middle of loads suggested in my Lyman book.

Loadtech calls that a 54,000 load at normal length less if the OAL is longer.

In my wife's 7x57 45 & 46 grs of h414 and a 140 would leave a raised primer. Loadtech calls it the same pressure as your 4350 load. 47grs and it went away.

Just looked in my Hornady II (yep old book). Lowest listed load for the 139 and Imr 4350 is 44.8. Max is 50.9

Since you are in the middle to low side of the range if it were me I would raise the load a little and see if it goes away.