Home Forums Hunting & Shooting Single Shots New MGM Barrel Order

I might try loading it up a bit, but 303 brass isn't as robust as 308 Win and most of the modern cartridges. SAAMI lists 49,000 PSI as the maximum pressure for the 303 British. I will probably work it up to about 58,000 PSI, checking the stretch as I go. My computer projections tell me that going from 49 to 58 KPSI with a 165 gr. bullet, should get me about 150 fps more. Velocities would go from approx 2690 fps to 2830 fps. You don't really get much extra usable range from the increase, from what I see.

My initial thought was that I expect the brass will take a beating. For the extra bit of velocity gain, personally, I don't think it's worth the bother, but I will have to shoot a bunch of loads before passing judgment. It should run through another accuracy node as well.

Since I'm a heavy and slow guy, I will be curious how much difference the extra PSI will mean to the 220 gr Hornadys I have piled up here. My good loads averaged 2100 to 2200 fps, and were under an 1.5 at 100 yards. I expect they should increase by about 100 fps or a bit more.