What kind of material do you guys think a T-Rex's skin was made out of?!
I would venture a guess that alligator and crocodile skin is as close as you'll get to similar skin texture and roughness/hardness of a T-Rex. A 7.62 x 39mm round will tear that up, no question. Throw in a 75-round drum magazine, and you should have plenty of firepower to take a T-Rex down.
