I think this is a very good grenade launcher. It has some down sides but I think that it's pros out way the cons. I own a Jing Gong M4 6604 I think and it fits pretty well but you will have to play with the battery to get it to fit in the top instead of the bottom and have to push around the wires just a little. I hooked mine up to the barrel instead of a rail and one thing I didnít like was that I had to pry the front latch open with a butter knife and because of that I just used a black twisty tie to connect the latch. I highly recommend this Launcher and the Mad Bull XM204HP King BB Grenade Shell.
Long enough for the King Grenade
Everyone will fear you
As heavy as my gun (but that isnít a con to me, though some people might think so)
Hard to get on at first
Comes with no instructions
Rating: [4 of 5 Stars!]