Muroms for magnums

[Laurie]

Yes Montey - usually plus half to three quarters of a grain to restore MVs to previous standard (large primer) levels. See part 1 of my follow-up series on testing SR primers in 308 Win Palma brass where I used new standard Lapua brass alongside the Palma version as a 'control' when working a test load up.

I this case (with Viht N150), it needed ~1.4gn extra powder to produce LRP MVs. !!!

SR Primer Test part 1

SR Primer Test part 2

SR Primer Test part 3

However, even in a basic side by side test working a load up between the two types, the Palma case did exactly what it said on the tin. You do need to return to your load development though and refine the combination to get the best results from the new case.

[VarmLR]

That is an excellent and very informative series of articles Laurie, and I only wish that I had read them before plunging into my 6.5 SR brass load development as it would have saved a lot of head scratching!  It also serves to highlight something which I, for one, was happily oblivious to with my factory Tikka TAC, and that is the possibility of blanking or cratering, something to be very wary of now you've pointed it out.  My own experiences with 6.5mm echo precisely what you have found in .308, and that is MVs, hence chamber pressures significantly down on QL or manufacturer's load data compared with LR brass, but tighter ES, in my case resulting from the off with ES figures in the teens.  I'll post my results using Magnum primers with the same loads and also load up in due course to find the higher loading sweet spot over my current, presumably mild loads.

[Montey]

Laurie many thanks for your reply the articles have saved a lot of gues work .