I'm thinking about getting an upper for 3-gun competition and need some advice. I currently have a pretty bone stock 20" Armalite A2 that shoots well and I like it as a varmint/predator rig. However, its a&& heavy - especially with the big ol piece of glass on top. Would i have any performance issues with snapping a different 18" or 16" upper with a lighter profile onto my A2 Armalite lower? Do i have to stick with a rifle length gas system with this lower or would it run with a carbine length? Budget is a consideration so I'm trying to find the most cost-effective way to get to a solution - not sure a completely new AR-15 would fly with the wife.

I am new to the AR world so forgive the basic question. I have plowed through a lot of posting out here trying to answer this and am still a little confused. Any advice appreciated. Thanks.

Husker