Live Fire Pulse Rifle

[SciFirepower]

While I was putting together a plan for my latest Pulse Rifle, I realized that I was within reach of building a live-fire one and decided to go for it.

Base gun is a semi-auto M1 Thompson with the barrel shortened and turned down. The Thompson also has a modified grip and extended cocking handle.

The "grenade launcher" was a lot more work. The original gun used a Remington 870, but MN has a prohibition on short-barreled shotguns so I decided to get around this by using a Remington 760 Gamemaster in .30-06 instead. The Gamemaster is very close in design to the 870, but is a rifle. Many of the parts are interchangeable. The gun had to be shortened and heavily modified. Adding a Troy Claymore muzzle device helped the .30-06 barrel fill out the grenade launcher muzzle.

Both the Thompson and 760 are registered "Short Barreled Rifles" in accordance with Federal law.

SPAS12 parts were sourced from a Tokyo Marui Airsoft gun. It's essentially a sleeve that fits over the 760, and will not be subject to extreme heat or recoil shock. I coated the inside with epoxy to add strength but it hasn't been a problem. The 760 is mounted directly to the Thompson's forend bracket. Other Pulse Rifle parts are from Hollywood Collectibles Group (HCG), Matsuo, and SD Studios.

I added a Bushnell TRS-25 optic, but may replace it with something else in the future. I plan on using a modified counter from James Forder. Still figuring out the switching for that.

 

[Dean O]

Looks great! Seeing that yours is a 10-hole variant makes me happy too!

I am jealous that yours really fires. I built an airsoft version from a Tokyo Marui Thompson, real SPAS parts, machined my own barrel vent and stock, and a generic airsoft. I finally finished it few years ago. I’m really surprised by how good that airsoft SPAS cage looks, at first I thought it was the real thing.

 

[Lear60man]

I think I know the answer...but did you just cut the barrel on the TM-1? I always thought about how I was going to tackle that part, 10inch barrel?? Your path makes perfect sense.

 

[SciFirepower]

We shortened the barrel to 10" and then turned it down on a lathe to remove the taper. I also had wrench flats added to make it easier to remove.
I've seen other folks just shorten the barrel, but the taper looks off and doesn't really fit the barrel vent.

You can't just unscrew the barrel from an M1 Thompson. You really need a gunsmith that specializes in Thompsons to do it. I used Philadelphia Ordnance for the job, and they did great work. Once the barrel is removed and the threads cleaned up, it can be easily installed and removed. I added some wrench flats to help with the process (highly recommended).

I've seen some folks have the gunsmith put a set screw in to keep it from backing out, I plan to do that in the future but so far test firing it hasn't been an issue. Look up "M1 Thompson quick change barrel" for info on that.

The barrel vent was from Matsuo and had to be modified to fit the Thompson barrel. We cut off the ring and fabricated a new one using a portion of the cut down pump tube from the Remington 760.

If I were to do this again, I would get a vent from Matthew Hudson at Prop It Up. Matthew sells a number of other M41A parts as well.

Honestly, the easiest part of the project was modifying the barrel. This is not a simple project, you have to do a lot of fitting and fabricating.

 

[yaris]

A dream project for me but where I live practically impossible to achieve. Well done, it looks completely authentic and rightly so...!!!

 

[Metalalien]

Be careful it will kick some.

 

[SciFirepower]

Still some work to be done, but it's looking good on the wall with my Ithaca Stakeout