I have a RIS rail, but took the bottom part off so I could mount the 203 directly to the barrel...but, it's all gone a bit wrong. The Classic Army M203 turned up broken, part of the metal was snapped off which was the part that attaches to the base where the barrel meets the lower receiver...when I opened the box and there was no front mounting kit which attaches to the barrel past your front site..so no way to secure the launcher. I'm in contact with the supplier regarding this...broken launcher and no mounting kit.What make of rail have you got on your m4 as I've been looking for 1 that will allow me to mount my barrel mount m203
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