primer pockets shrinking?

[wayne h]

In reloading for 30-06, I use the same brass in 1 rifle therefore neck resize only. I have fired this brass several times w/a lyman 311291 gas checked bullet using either 16.0 grains of 2400 or 42.0 grains of H4831. I am now finding the primer pockets seem to be shrinking as it is requiring more pressure to reprime. I know this sounds crazy. Is this normal? Wayne h.

[frkelly74]

Mine expand and get loose if they change at all. Different lot of primers??

[Char-Gar]

No this is not normal..in fact quite odd. I would tend to think you have changed primers or take a look at the tool you using to primer the cases. I don't think the problem is with the cases.

[swheeler]

Are the primer pockets clean?

[madsenshooter]

I got some Winchester primers not long ago that had quite a bit of variation in cup shape, overall thickness, and diameter. The differences were for the most part minor, but enough that I wouldn't use them for match loads.

[3006guns]

You didn't mention if the cases were commercial or military. On military cases I use an RCBS primer pocket swaging tool to remove the crimp, but also use my beveled case mouth reamer to cut a small bevel on the pocket edge to allow easier seating.

What does this have to do with your question? Well, I have experienced something along the lines you describe. I don't have an explanation but I run them through the pocket swaging once again and that usually solves the problem for good. Maybe I didn't swage sufficiently in the first place...add a little crud after firing and it becomes a tight pocket again.

If they're commercial cases with no crimp then it almost has to be a dirty pocket or something fishy with the priming system. As mentioned, if the primers are all one manufacturer that could be the problem too. If you could "borrow" a different brand, try them and see what happens.

[Gtek]

In the last year I ordered several hundred Winchester and I was very disturbed by quality. Using the term JUNK is being nice. Sent all back to supplier and left comments on their site. I was very suprised when I was contacted by Winchester and they were very nice and said they would send me new to correct issue. Well it arrived three days later, 200 more rounds of JUNK. I returned them and told them I was done. Yes I am picky! 30% was .010 shorter than min trim length, some necks were .004 out. I am an old Win fan, it hurts. Gtek

[wayne h]

I am using a combination of Hornady,remington,federal and winchester brass all civilian brass, pockets are clean. This is only happening w/the Hornady and remington brass. The primers are old CCI, that I bought in brick form at a garage sale, all boxes labeled as Large Rifle. I will run these pieces through a military swaging die and see if it helps. Wayne h

[firefly1957]

I would look for build up of residue.

[303Guy]

Might I suggest that before you do anything else to those cases, to measure the primer pockets or if not possible, to find someone who can measure them? It might be revealing! After all, no-one has heard of this before. But if it happened to you it might actually happen from time to time without anyone noticing. You have the pieces that could tell us something new. There could be an anomality in those cases that allow the brass to flow or compress in the pocket area without expanding the case bases.

[mroliver77]

Two different makes of brass? I would say it is the primers or something in your system. What that could be, I am at a loss. I have cutters to uniform primer pockets and use them on most all my brass once. Boy do they feel nice while seating afterwards.

I second some precision measuring before doing any swaging.
Jay