I had two AM180's - great little guns. And now with the rising cost of ammo I really regret selling them. They can be a little finnicky and they definitely have a bit of a learning curve to really get to know how to run the gun and keep it running. Some types of ammo simply just won't work and the guns are prone to breaking the selector bar, especially if you do a lot of short bursts. The more you stop the gun in the middle of a mag, the more likely you are to need a new selector sooner. The feed blocks can also be problematic and often need to be set in place with set screws.
Drums are available in 165, 177, 220, and 275rd capacities. Loading a drum can take 10-15 minutes or longer, and with its high rate of fire, it only takes about 9-10 seconds of trigger time to empty a 275rd drum. Jams can be difficult to clear and if you get a round loaded wrong in the drum it can be a real problem to get out. IIRC the Yugoslavian military flirted with a version of the AM180 (the MGV-176) but I would definitely not trust my life to one. They're a lot of fun and a great "toy", but not sturdy or reliable enough IMHO for that sort of use.