R-P 6 1/2 versus 7 1/2 Primers?

[jimfinn]

As everyone knows getting components is a bummer of late. In AK we don't have a cost effective way to ship powder and primers as there is no real UPS Ground from Outside to here. So I'm stuck with what the local stores get in.
I am working with my first 6 BR rifle. I have some,about 400) Fed 205M, and Remington 7 1/2 Benchrest,about 600) primers. A local store had one carton of 1,000 Rem 6 1/2 primers, so I scooped them up.
I went on Remington's website and they gave no explanation on the difference between 7 1/2 and 6 1/2 primers.
Can anyone enlighten me? Is it probable that any loads I work up with the 6 1/2 primers will be of no use with the 7 1/2 primers. What I'm thinking of doing is using the 6 1/2 for initial load development and save the 7 1/2 primers for final tweaking and loads.

I've read that some folks really like the CCI BR and 450 primers are best. Heck I was able to pick up a 1,000 CCI BR-2,Large Rifle) primers in the same store, but no luck with Small Rilfe there.

Thanks
Jim

 

[nfa1eab]

Jim,
I am shooting a 6 BRX. My experience with Rem. 6 1/2s goes back to service rifle in an AR-15,.223). They were soft primers and I had problems with them piercing easily with match loaded ammo, probably on the warmer side of things. I switched to Rem 7 1/2s which are benchrest/match primers and much harder cups, and never pierced another primer, period.

I have used them,7 1/2s)in my 6 BRX and got good results with 105 Berger VLDs at up to 3,050 fps with no pierced primers. The load was warm for sure, but the primers were no issue. I switched to Fed 205Ms because I had them and wanted to go to a milder/more consistent primer then the 7 1/2s. The extreme spreads came down a bit along with the SDs. My Remington bolt has been bushed by Gretan and the firng pin size reduced, which seems to help the primers take higher pressure loads. Even with the 205Ms, I have shot loads that showed some ejector marks on the brass without primer piercings.

I am still trying to get some CCI 450s or Wolf SRMs as they are tough primers with milder ignition. They have been harder to locate than Hen's teeth and Lizard's fur.

As for the 7 BR brass.....Buy Lapua. Quality is outstanding, and they will still be shooting when the primers are falling out of the Remington brass, which may be 1 or 2 firings if you load on the warm side.

Probably not what you wanted to hear, but thought I should share my results, and maybe save you some aggravation and bolt face scarring.

Sorry for the long reply. My $.02

Ed

 

[jimfinn]

Thanks Ed,
I figured there would be a real difference between 6 1/2 and 7 1/2 primers.
As for the Rem brass, as I went to bed last night I remembered that it too uses small primers. It is the flash hole that is a bit larger than in Lapua brass.
Jim