Are you talking about an M1-A or a Polytech "M-14"? If so, to convert either one to burst fire is a felony. You'll lose your rifle and your freedom. You cannot make a legal auto out of a semi-auto. It is against the NFA.
I'm not talking about an converting an M-14 or m1a, I'm asking if one exists. I was wondering if the military has produced or developed one. Also, the M-4 is the carbine version of the m16 not the m14. I was wondering if the .308 M14 was ever made into a burst fire version.
Roger on the M-4 / M-16. I think that was just an oversight. No, there was no issue version of the M-14 that was made with a burst selection that I can find reference to. That was one of the problems with the M-14. Even a big guy has a hell of a time keeping it anywhere near the target on full auto. Burst might have made a difference. As it is, even with so many taken out of storage for use in the sandbox, I doubt whether they are going to make any major mods on it.