I have been seriously contemplating getting a new/used 1911 (something sub-5" in .45 and American made would be nice.. oh, and under $1000 would be just swell...) And it seems as though I keep reading that certain things need to be replaced/upgraded as soon as you get the gun. Be it the trigger, beavertail, or some other part.. My question is why. What makes the factory parts less than optimal?.. Without getting into the "because I can" or "because I want to" arguments, what should I know?.. Oh, and I realize that parts break, but if the gun is new- do I still need to replace certain things?.. Thank you..