Hello I was wondering if anybody has swiiched out the standard A2 size butt stock for the earlier A1 style butt? I've read that the A1 is 5/8" shorter in length and the screw to hold the stock to the tube is correspondingly shorter too. Does anybody know the specifics like size and thread pitch for this screw or do I have to cut down an A2 screw? Thanks in advance. Cheers