The buffer length on my pre-ban Car15 is 3 1/4 inches, and the inner length of the buffer tube from the back wall to the retainer pin is 7 inches. I'd say that if your equivalent dimensions are more or less the same, you're OK.
By the way anyone who tells you that the buffer is a"full Auto" part is either pulling your leg or needs to learn more about ARs before they post anything. [:D]