Shouldn't be a problem, IMHO. I am not a gunsmith/Guru/expert, but I have been around 1911 type guns a fair amount over the past 40+ years. As long as you have a super barrel that fits properly and a Super magazine, the only thing I can think might be an issue is the ejector. Some 9mms have REAL long ejectors. This may prevent a loaded super round from being ejected if you need to clear the weapon with a loaded round in the chamber. I just used the shorter .38 Super ejector in my '70 Series Colt I had set up for both 9mm and 38 Super. The super case rim is slightly larger in diameter, but usually not enough to cause any problem at all. Some manufacturers now days use a .40 cal. breech face for .40/10mm and anything smaller anyway. My kimber .38 Super and Kimber 9mms were all that way. All 100% reliable. With Colts manufactured in the last several years, the only mechanical difference between the Super .38 and the 9mm is the magazine and the barrel. I have a new Colt .38 Super that I'm going to set up to use both calibers. The only changes I intend to make to use 9mm, are a 9mm barrel and magazine. ymmv