Preimer pocket prep

[jmason]

Originally Posted by Winchester 69

And for re-setting the cutting depth when it self-adjusts. RCBS?
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Yep. RCBS. I have it bottomed out. My thought was the pressure on the tool is always downward (have trim mate) so it should stay there. Unless.......

Charles

I guess the misfire concern came from seeing the primers below the base of the brass. I'm suprised primers don't get peirced when you don't uniform the pockets. The primers appear lower to the naked eye. I did notice before doing this that some primers didn't seem to sink the entire way in before.

[Winchester 69]

The benefit of uniforming the primer pockets is that the primers seat completely.

Pierced primers are caused by excessive clearance between the firing pin and its bore in the bolt. The metal is extruded into the gap.
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[anachronism]

Most primer pockets are swaged with a tool that's slightly tapered. It has to be tapered to allow the tool to be removed easily. When we uniform primer pockets with a reamer, we take that taper out. My experience has been that this could decrease primer pocket life a bit because primers in factory pockets seem to seal more towards the bottom of the pocket, in this tapered area. Most primers that I bothered to measure (I was bored) had a slight taper in the opposite direction and were larger at the mouth of the primer. I know this is really hard to follow, but think of two cones one slightly smaller than the other, placed mouth to mouth. One mouth will fit inside the other, then go a short distance before it can go no further. Hopefully, I'm not too tired right now to explain this coherently. I'm sure I'll get flamed anyway...

[jmason]

makes sense to me. by the way I had no misfires.....