When you install the plastic butt stock, take care not to over tighten the retaining screw. If you do the gun won't function, so just snug it up lightly and use the lock screw to prevent things from moving. Its not like a butt stock that has the bolt running lengthwise through to the tang or the receiver that has to be torqued really tight to keep it in place. The little screw on the A-5 just has to be there.