I haven't ever owned a semi-auto pistol (but Obama may be begging me to get one sooner than later ) so I am obviously a little ignorant about the subject. What does ACP stand for? Regarding .45s what is a 1911? Seems like everyone makes one; Colt, Browing, High Standard. What is the difference between a pick-your-brand 1911 and say, a Ruger P90?