I'm going from memory, but didn't Sherman Bell do some test with 2 3/4" shells in 2 1/2' chambers where pressures only went up 500psi ? I would never remove any wall thickness where it's needed the most.
I think the caveat was that the 2 3/4” round had to generate about the same pressure as the 2 1/2” round the gun was designed for. Actual pressure on 2 3/4” ammunition isn’t something that gets a bunch of light shined on it from SAAMI spec manufacturers of same.
I’ve run the lighter version of 2 3/4” Winchester AAs in my 2 1/2” Halifax, damn if I could tell the difference between 2 1/2” RSTs, but, that gun is a brute in barrel construction and muzzle wall thickness. I’m in no hurry to run anything hotter in it.
Best,
Ted
