Drums for the AM180 and AM15 are available in three different sizes.   The drums are transparent plastic so you can see how many rounds are left in the drum.  Plastic mags have always been a problem, but since the mag uses the replacable feed block as the "feed lips", you're actually feeding through a steel lip mag.  The metal drums from the original AM180's feel more solid, but when you drop them ONE TIME, they get a dink in them and its virtually impossible to get them to spin freely again.  These plastic mags will take more of a drop and will crack rather than dent, so with a little super glue, you still have a shooter.
I'm often asked why would anyone want a 165 when they can have a 275 rounder?  Best reason is that its a good size to use when a newbie wants to shoot your gun... since they won't be able to tell the difference between 165 and 275 and you can save some ammo and some loading time!  It's also somewhat lighter if you have to carry the gun in the field and is of course faster to load.  For those of you that want to let'er rip, of course we also have 275 round drums... a picture of both together is show below for comparison.

The drums are loaded by removing the winder (not included with the drum) and turning the drum upside down.  Then using an optional loading tray, simply drop the bullets in as you manually turn the drum.  Drums are easy to load with a little practice, and the payoff is you'll have a volume of .22LR firepower that's unequaled by any other .22LR firearm!

PRODUCT SPECIFICATIONS
PRODUCT NAME	DRUM 165 ROUNDS FOR AM15
Manufacturer	E & L Manufacturing
Application	AM180 - AM15, Semi or Full Auto
Construction	Plastic
Caliber	.22 LR
Capacity	165 Rounds
Diameter
Height
Weight (Empty)