Primer seating problem

[Varmint Hunter]

I started with new Win brass in 7WSM, then ran a Sinclair carbide pocket uniformer into each pocket. Tried seating some new Federal 215M primers and they all sit a few thousandths high. I originally used a fair amount of pressure when priming with the RCBS O frame press but that didn't get the primers where they should be.

If I use a significant amount of pressure to further seat the primer I get a flat spot on the cup and the amount of force needed is beyond what I'm comfortable with.

Anyone have any idea what's going on here?

 

[Trickymissfit]

measure the reaming depth with a depth micrometer. Then measure the over all length of the primer itself. You should be able to seat the primer .005" under the face with little trouble. But the problem may not be in the reamer, but in the priming device. I use a K&M reamer, and it goes a little beyond that .005" number, but with my Forster press the primers are always between .004" and .005" under the face. Sounds like the depth is a little short for a Federal 215 primer
gary

 

[Varmint Hunter]

measure the reaming depth with a depth micrometer. Then measure the over all length of the primer itself. You should be able to seat the primer .005" under the face with little trouble. But the problem may not be in the reamer, but in the priming device. I use a K&M reamer, and it goes a little beyond that .005" number, but with my Forster press the primers are always between .004" and .005" under the face. Sounds like the depth is a little short for a Federal 215 primer
gary

Pockets measured at .129" deep. Primers varied but were generally .127"-.128". That would make a seating of .005" below the face impossible but should still work. Is it possible that the primer gets slightly longer when squeezed into a tight (narrow) pocket?

 

[Trickymissfit]

Pockets measured at .129" deep. Primers varied but were generally .127"-.128". That would make a seating of .005" below the face impossible but should still work. Is it possible that the primer gets slightly longer when squeezed into a tight (narrow) pocket?

there are two different thoughts on seating primers:

.004" to .005" under the face. The .005" under the face is also a saftey issue. In something like an AR you might have a continouis fire till the magazine is empty due to firing pin strikeing the primer as the bolt seats

The other is to seat the primers till a certain crush is gained (more like a feel). The Sinclair and K&M work off this principal. Yet the primer must still be under the face of the case. I do both ways, and can't see a lick of difference between them in my groups. K&M sells a priming tool that actually measures the over all length of the primer and seats it accordingly. How well it works I can't say as I've never used one
gary

 

[BlackStreak]

I have an RCBS hand priming tool that I've grown accustom to using instead of my rock chucker. I had the same issue not long ago with all my 338 Lapua brass. I simply put the shell in the rock chucker and finished pushing the primers in. I don't have to push unusually hard or anything out of the ordenary. I have even used multiple #14 shell holders in junction with the hand priming tool but made no diffrence. I don't understand y just that particular shell and y it only gives trouble in just the hand priming tool but we might share similar problems thus u might be able to overcome your issue in a similar fashion.