Sarcasm - Probably with the right cheat any gun, attachment or you name it is more than enough.
Okay any AR can have the Select Fire attachment if you want to make any gun a MSBS. My assumption is because of BO2 and the extremely low player use of Semi-Autos. I was Beast with the FAL and once I got the rhythm of the Chicom I was damn close to full auto. Reality check is in the military guns like the M-26 ... it only takes one bullet to put most enemies down and not 2-3 at close, 3-4 mid range and 4-6 at a distance like they do in 'games.' Pff if I shot you with a 22 in your leg ... what are you going to do??...jump off a roof, do a 360 and melee me!? No, you'll be dialing 911 while screaming in agony on the floor.
There's nothing, I mean nothing, realistic about CoD ... zero! If you want a War Sim then look at ARMA or in between BF4; CoD is an arcade shooter game. I have real guns and the recoil alone would end this conversation.
LOL......I don't need a REALISTIC, I was in for Eleven Years. What I'm referring to is the other "COD" games. They all had Selective Fire except for this game. Plus on top of that, they released the game 6 months too early. Thus all the damn "Bugs" that are in the game that will need several patches just to get it to run normally.