45 Super
I've been shooting light or (tactical as Triton used to call them 230g. @ 1000 fps) 45 Super loads in my P90 for about 6 months now. The P90 was originally designed for the 10mm, then produced in 45 ACP due to lack of the 10mm's popularity, so it can definitely handle the pressure. I definitely would not shoot 45 Super in just any 1911. I personally wouldn't try the Super without a ramped barrel, just because the 45 Super case is stronger doesn't mean you won't blow it out in an unsupported gun... just one mistake with a grain too much powder could be tragic. In addition I upgraded the recoil and firing pin spring. I went up about 50% in spring power and the P90 still shoots stock 45 ACP hardball just fine. Check out the real.guns web page and if you have questions, email joe at real.guns. He's real helpful. I agree with him that a lot of the stuff Ace custom guns does is just that, customizing, and not necessary for 45 super, but you want a strong gun with that supports the case well. I hope your guns support the 45 Super, 'cause its fun to shoot and it sure makes a stopper out of the .45 auto...