I've really only noticed it when I've used the Gewehr 43 but I'm a noob so I don't have much unlocked. Anyway, sometimes I'll be shooting someone and all of a sudden it's like the R2 button just stops working. It's so annoying when I'm about to kill someone then it stops. Usually it'll start firing again a second or two later. I haven't noticed any problems with my R2 button in any others games either.