Primary weapon won't fire R2 trigger changes to secondary

Hi.

I've actual had this problem from the beging. Only happens every 15 or 20 games but the R2 trigger switches to secondary wepon then fires. Y changes back to primary but then as soon as I pull R2 it changes to secondary and fires. Only way to get rid of it is to get kiled. When it's doing this it seems to happen through out the game. Next game usally no issues. weired bug.