I'm working on one of my first replica builds and well its a big one to me. I've always had the dream of having a live fire sbs/sbr m41a pulse rifle from aliens and I've almost collected all the nessasary parts( hcg shroud, spas 12 cage, extra). My question is how did they secure the launcher(remington 870 Inside spas 12 cage) to the fore end of the m1a1 thompson? I plan to shoot super light loads so I'm not worried about it snapping off. I just want it to be screen accurate. I couldn't find any detailed info on this and I know I'm not the first one to attempt a firing pulse rifle. Any help in the right direction would be awesome. Couldn't find a thread on specifically the launcher.