Loose Primer Pockets

I occasionally read comments about loose primer pockets or reloading brass until the pockets will no longer hold a primer. I have always associated that with over-max, over-pressure loads and have never experienced it. How common is it? Are there particular brands of brass/primers/loads?

Yes, if you fire a case enough times, the primer pocket will become loose, and no longer hold a primer. That's when it goes into the trash can. Normal firing under normal pressures will have normal wear on the brass. Hotter loads will certainly progress the swelling of the primer pockets. I've seen as little as one firing to 2-3 firings on warm ammo. And yes, there are certain brands of brass that wear out the primer pockets quicker than others.

For example, I have a customer that I loaded a bunch of 338 Edge +P ammo for. It's a long lead chambered throat that handles higher pressure better. The data showed it was a 70K-72K psi round. The 338 Edge is based on the 300 RUM case, which is a rebated case design (meaning the case head is smaller than the width of the case body). So, there is A LOT of pressure coming back on the bolt and case head. After he shot those rounds, the brass was done and would not even come close to holding a primer. So, that expensive brass and load was a one shot only load. That's the cost to pay to play.

Also, take the 6.5x47 Lapua case. It is a normal 308 case head size, but fires a small rifle primer. There is a lot of brass around the primer pocket for added support, so it does not swell as bad as the same size case head with a large rifle primer, like a traditional 308 or 6.5 Creedmoor case. I know shooters who have 18-20 reloads on their 6.5x47 brass. That's good!!