Priming 470 N.E.

[Alistair]

I’ve found the same with my 9.3x74R Norma brass. Few cases were so tight that I stopped with primers seated half way, I was not willing to apply any more pressure for fear of detonation. The 470 brass I’ll be using is from factory rounds I shot so hopefully the pockets won’t be so tight.

What did you use to expand the primer pockets?

I too have found this with Norma brass, in .270win, .375H&H and in .308. They seem to make them pretty tight as standard, so if you use primers which are on the larger size (Federal as an example) they're really tight to seat.

I just use an RCBS hand primer, do it outside and wear safety glasses, but it is a lot of force to apply to the primer and a touch fraught (I never had one detonate though). CCI primers will work much better on that first firing as they're a little smaller in outer dimension.

At least they loosen to an acceptable level after 1x firing and the brass quality is really good, so I tolerate the inconvenience.

Back to the question at hand; a hand priming tool that uses standard shellholders is the answer. I had an RCBS one that came in a rockchucker kit, but they're all much of a muchness and work just fine.