If my bayonet lug is "loose" can it make my bands move after firing?

Yeah, I'll just get a new one. The stock that the rifle came in when I got it isn't the prettiest and isn't the most functional either. It'd have to go through alot of work to be shootable and not have it disintegrate after three rounds so the band might not work that well on that one either.

Two other things you can do if you REALLY don't want to get rid of that band. Knock the dent out of it, but you might also get a stronger spring. Some of them have a more aggressive bend than others which makes them very stiff. You can also shim the spring you have by putting a little folded paper between it and the stock, essentially making the channel it rides in shallower. You won't need much - think a sheet of A4 paper folded over two or three times. Either one of those might make the engagement between the nub and the band positive enough to not pop out under recoil.