Off the beaten path weapons?

So as a part of a few of these quests I have stumbled on some really awesome, fun, and effective weapon/builds/load outs.

Doing the kill PMC's with silent shotguns and hitting the buy limit for AP-20 on mp-153s, I tried out Magnum buckshot and it is very very effective. It is still a shotgun, but if there is no face shield, point fire a saiga near and head and it is an instant kill. Great for factory. Also, Deadly slob did a video showcasing it and the arm/leg damage alone is effective. Really fun for factory. I tried fleccette and it felt like I was shooting BBs.

Also I tried out the MP9 sub-machine gun that shoots 1100 rpm with 6.3 AP and a laser and it is a very very cheap CQC shredder. Super fun. Level 4 armor gets melted.

Its nice to break up the AK and mosin runs. What have you found effective this wipe that was something new?