The Grenade Launcher

I had a major victory a few days ago. I was able to fit the Maruzen M870 into the SPAS-12 hand guard. Here's what it looks like:

I found that the width of the inside of the SPAS hand guard was too narrow to fit the M870 inside it without either distorting the hand guard (from it bowing outward) or cutting a shallow channel into the left side of the M870 receiver so that the pump groove of the SPAS cage can slide across it without distortion.
From these pics, you can see that I still need to cut the shell ejection port hole on the right hand side of the SPAS hand guard. I've marked it's location and shape in white colored pencil. On the left side, the slot for the racking arms to be connected to the pump grip is needed. The trigger guard of the M870 also requires some trimming to be accurate to the 'hero' Pulse Rifle.

I can't wait to get the whole Grenade Launcher behind me. I'm going to start working on the hardware to connect the racking arms to the pump grip so that I can cycle shells through the M870. It's probably the most complicated part of the build. Luckily, it's also probably the most rewarding part too. Collecting all the parts was the biggest challenge in my opinion.