338LM Peterson brass, primer pocket!?

[Fire Dog]

That probably would have been the typical path but after trying this/that/reaming/swaging I feel like I signed up for the ride, its completely possible that its something I'm doing wrong.

I did a bunch of pin measurements, these pockets are 0.209 dia x 0.128 deep. So no mater the primer they are of a usable size. I'm having some doubts about my press's ability to get things seated flush (feels like its bottoming out.
That could be be due to my 45-70 shell plate converted to 338LM (because a 338LM doesn't exist), shell plate isn't holding it tight enough to the press. I bought a shell holder for 338LM to use my RCBS bench primer but its MIA
I did find a major malfunction and the reason they've been hard to chamber, some dummy seated them 0.060 into the lands (DOH). Bullet comparator and print math got me close but the old jamb test showed I needed some more.
The running theory is I'm crushing not flush primers when chambering. I've pulled bullets on previously seated rounds and the primers have been igniting.

So I have a stack of the corrected bullet seating depth rounds to test.
I've crushed primers- these are not getting that kind of force.

I’ve used Peterson brass for years without any problems though I do not have any 338 I do use it across three different calibres.
I always have primed them with a 21st Century priming tool and not on a press as the tool makes it easy to adjust seating depth rather than going by “feel”… Quicker as well…
Perhaps that would solve your issue as you mention that the shell holder you are using is not correct for the case but a modified one and not allowing the press to fully seat the primers.
Just a thought…

 

[JGSprecision]

I’ve used Peterson brass for years without any problems though I do not have any 338 I do use it across three different calibres.
I always have primed them with a 21st Century priming tool and not on a press as the tool makes it easy to adjust seating depth rather than going by “feel”… Quicker as well…
Perhaps that would solve your issue as you mention that the shell holder you are using is not correct for the case but a modified one and not allowing the press to fully seat the primers.
Just a thought…

Totally agree, the bench primer would solve my flush issues (according to my pocket as well).
Great would be a priming tool that clamps the base flat and isn't affected by rim thickness (sure its been done).

 

[ebb]

You have this figured out get the pieces you need and save the frustration for something else, this is supposed to be FUN!!!! Good luck and show us some great groups!

 

[JGSprecision]

Well I'd say a good uniformer like the K&M tool is a must with this brass.
Now I can seat WLRM primers no problem.
Also machined primer seater on my LNL AP for a bit more stroke (compensating for my converted #14 shell plate) so now I get flush seating on the press.
Testing time!
FWIW, it was mostly a priming tool problem but that doesn't explain why the same press could prime S&B brass (before modifications). Maybe thicker rims?
There had to be radii in the corners of the pockets causing the anvil to smash the priming material. The K&M tool certainly removed a bunch of brass.