Are there any differences between an a3 and an a4 upper reciever?  thanks in advance!

A3 is fixed carry handle , A4 is removable ..... as far as M-16s go

In the AR world A3 is removable, and some call the removable handles A4s to match what the M-16 designation is.

Almost. With M-16's, an A3 is an A2 with full auto instead of 3rd burst, and an A4 is the flat-top. For AR's there's the A1 (C7), A2, and flat-top, which most companies refer to as A3, but a few (Colt, Rock River,ect.) use the military designation A4.

Thats what I said. The question was of upper recievers only. There is nothing that makes a A2 upper reciever any different then an A3 upper reciever on an M-16 since that part does not effect the fire mode. So  the question was whats the difference beteen an A3 and an A4 upper reciever. The answer is the same I gave. Your answer would of been good for whats the difference between an M-16A3 and M-16A4 RIFLE.




and yes..... I'm a smartass [:)]

so am I[;D]