The 3 mounts in the box are designed to make the launcher fit on different platforms. The first one, which is already preinstalled, is the barrel-mounted version for the M4 series. It clips into the outer barrel at the rear and then hooks over the outer barrel on the front. The second mount is a 20mm RIS mount which will make the launcher fit onto any 20mm Picatinny rail and the third mount is is like the rear barrel mount, but can fit onto SRC and Tokyo Marui standard M4’s where the delta ring is a different design.

The Long version of the M203 is better equipped on M16 length barrels which are from 15″ onwards. This is so the barrel from the grenade launcher doesn’t extend further than the barrel of the rifle. Loading the launcher is easy, just press the release lever on the side and slide the tube forward all the way, put the moscart in the hole and pull the barrel back until you hear it lock. This does NOT come with a moscart.