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.

The M870 Fiasco.

I wanted to post a picture of my Maruzen M870 airsoft shotgun, and a brief explanation of what I went through to get one. But first, a picture:
So this particular airsoft shotgun is not manufactured anymore. It is a pretty high end shotgun with realistic action. As it is a very good replica of the Remington model 870, I figured this was the perfect choice for the guts of my grenade launcher. All I had to do was find one. After weeks of searching locally and online, I found a seller and sent funds in exchange for a used M870. I went through nearly 4 more weeks of hell trying to get the seller to ship the item to me from the east coast. Lies were told, excuses made, and in the end I had to demand a full refund and continue my search. It was awful.
The day I received my refund, I managed to find another one. It is practically new with all the packaging, instructions, etc. I told this seller of my previous hassle and he took our transaction very seriously. I received my M870 2 days after payment. Here it is in all its glory. Now I'm going to start taking it apart and chopping in down to size so that it can fit inside the SPAS-12 hand guard. It will never look like this again. I think it's worth it.

Shrouded in mystery

Yesterday I started drilling holes in the SPAS-12 hand guard for the Grenade Launcher front block. I quickly realized that I needed a few new drill bits as mine weren't sharp enough. You don't want bits walking on you when trying to drill something as rare as a SPAS-12 hand guard! With the holes drilled, it was time to take the Dremel to the opening so that the block would fit in. That was really easy.

I also measured and drilled 2 holes in the base of the barrel vent to mount it firmly to the top of the SPAS hand guard. The first hole is at the front and lines up with the threaded hole in the top of the front block. The other hole is near the middle of the 10 vent holes. A hex screw secured by a nut inside the hand guard completes the mounting.

Once I had these parts aligned and properly attached to one another, I felt like trimming the shroud to fit would be in order. I didn't want to do this until the metal parts were. Trimming the shrouds went quickly. Granted, there is still some minor trimming left to improve areas like in front of the Grenade Launcher trigger guard and also the magazine well is a bit too tight. Overall, the amazing castings and pre-assembly from Matt (Matsucorp) are the reason my work is easy.

That's it for now. I'm focusing on cutting the shell ejection and loading ports in the SPAS-12 hand guard next. But before that, I have to get the grip chopped down to size. That should be fairly straight forward...I hope!