Aut cum scuto aut in scuto
The muzzle blast and flash must have been a sight to see, especially if this M-14 is equipped with a giggle switch. The recoil would be a beast though. I carried a full auto M-14 as part of a Navy security force in the 1980's. Probably the most fun you can have without taking your clothes off.
Probably wouldn't cycle for more than five rounds without short stroking. The froggies have always had a thing about cutting the dick off of their weapons and turning them into Jam-O-Matics. He would have been better armed with almost anything else. And the uniform says Vietnam but everything else screams Reeinactor. I have NEVER seen photos of VN era froggies with bling on field uniforms. They ALLWAYS went out "sterile"---Ray
Don't go out without your Ka-bar for those times when it gets up-close and personal. And also, mind your trigger finger.