I've got a .400 Cor Bon Barrel from Jarvis
I've read that the .400 COr Bon is limited to 155/165 gr. bullets
because the 180 gr. and heavier bullets are too long and take
aaway from case capacity when seateed to correct O.A.L.
ALso, on the Ammo Can / 1911 Forum board a couple of years
ago a rep. from Cor Bon said the SAAMI rates it at 23,000 CUP
which is the same as .45 ACP +P.
Many moons ago, I loaded and fired over 10,000 .400 Cor-Bons and over 3000 .40 Supers. .40 Super is a superior round, but there just wasn't factory support.
I was having trouble getting .400 Cor-Bons to feed from my double-stack G21 magazines; blew up my first G21, and later discovered that the Klintonista G21 mags had a shallower stack angle and fed .400 Cor-Bon o.k.
I was getting a lot of advice at the time from Peter Pi, Prez of Cor-Bon. He suggested that I cannelure and roll-crimp my .400 Cor-Bon brass into the cannelures, in order to mitigate setback. Peter confirmed to me that the only reason they didn't recommend bullets larger than 165 grains was because they'd be competing against their own 185 gr .45acp +ps. There's absolutely no problem with loading 180s.
I fired most of the .400 Cor-Bons through G21s, but do have a .400 Cor-Bon barrel (all of my .400 Cor-Bon barrels are threaded and compensated) for my 70 Series Gold Cup. Never had any feeding problems with the 1911 single-stack.
Having wasted a lot of $$ and time before "discovering" 10mm, I sure do wish I'd made the 10mm discovery a few years earlier than I did.
Setback can be a bear with the short-necked bottlenecks like the .400 Cor-Bon!