Bakers Dozen is a classic M1A that people have been calling overpowered for a while. Just a named M1A rifle. They nerfed it a bit but for me it still is my preferred primary weapon (and it is also for my coop partner.)
I HIGHLY recommend getting the Bullet King exotic LMG. The ability to just unleash on rushers or a big yellow guy with non-stop firing (no need to reload) is amazing. We farmed for one for my partner, he really wanted one after he saw me using mine. He loves it now. The way you got it previously is you ran one of two missions in NY; one was Wall Street, the other was the Tombs. The final boss on those would eventually drop it. Problem with the Tombs is the final battle takes a long time if you’re farming (due to the design of that battle.) The first time my coop partner and I ran Wall Street, as part of the manhunt missions in WONY, the last battle kicked our tails. We would get overwhelmed, overrun, use up armor kits, run around like crazy, and then die trying to take out the three big yellow guys who stuck together. It took us forever to finally beat it, with slivers of armor and health left. And we were maxxed out levels. We were both using red/dps builds.
This time we got to the last battle, took a deep breath, full skill builds, ran and jumped into the area with the armor and ammo crates, put our skills up on the walls around us, ducked, and our skills quickly took out two of the three big yellow guys, and my Bullet King and his rifle and our skills took out the final boss, all in less than 2 minutes. Literally. Once we killed him we waited for the waves of bad guys. Nope. Mission complete. Could Not Believe It. BK didn’t drop, so we ran Wall Street again. Got to the final battle. 2 minutes, done. We did it 5 times and the BK dropped for him.