The info I found states that the 405 is about 42,000 to 45,000 depending on the load. The 9.3 apparently has no SAMMI standard, but the ACCURATE powder company tested Norma factory ammo at 47,000 psi. I'm thinking it's on the verge of too much for a converted shotgun. In Brown's book he states the 9.3 is a "medium pressure" cartridge in his appendix. I just really want to take the pressure thing seriously. I don't want to put a bunch of work inot this rifle and have it blow during proofing.