Thread: The Importance of Using the Right Data

Originally Posted by grandpamac

Greetings Moa Hunter,
Proof cartridges are rated for pressure and not load. The powders used are unlikely to be anything we have heard of. Pressures are significantly above the standard cartridges. Hatcher talked about proof cartridges for the .30-06 with pressures of 70,000 and 120,000 CUP. The normal max being 50,000 CUP. The .270 Win has not suffered the same reductions as some others. ADI list the max pressures as 52,000 CUP or 65,000 PSI. Most of the Hodgdons/ ADI load data approaches these pressures. I assume that you mean AR2213SC rather than the obsolete AR2213 you mention which is a little faster. Hodgdons lists 60 grains of AR2213SC/ H4831 for both the Hornady and Barnes TSX projectiles as max. This is the same load that O'Connor touted from the late 1940's so it should be safe enough. I am a fan of validating the data using my chronograph. If your rifle produces much the same velocity (making allowance for different barrel length) as the load data then the pressure is likely to be much the same.
Regards Grandpamac.

What you write re proof powders / loads may very well be correct, but I hazard it is a guess. How do we know what powders and loads are used ? Perhaps common powders are used. It would be useful to me if pressure was always quoted in load data so that I knew how close to 65,000 I was. Certainly some load data does quote pressure. I thought O'Conner used IMR4831 not H, anyway I dont really like 2213, just used it as an example.