I know my brother put a A2 stock on his Daniel Def. carbine. A friend of his asked him why, he walked up to a tree and butt stroked it, and asked him to try it with his colt M4 witch of corse had a collapsible M4 stock. He laughed and declined.
I personally love the fact that the A2 allows you to store a cleaning kit in the stock as well as other items, like matches etc. And for myself is a great length, and if it's to long for you, most will then like an A1 stock. It's also obviously much stronger. And if you were actually in a combat situation is very useful. NOT for buttstroking so much as dropping to the ground as trained (in the Army anyway) using the butt of the rifle to break your fall, since you are not exactly taking your time. Slam the butt of the rifle into the ground at an angle appox 45%. And it works well to help break the fall but still drop/slam to the ground in a big dang hurry.,,,and yea you can butt stroke someone with it lol. All things you can't do with a collapsible unit...or are taking a risk in damaging the weapon imo if done.