Posted: 1/19/2026 4:42:27 AM EDT
[Last Edit: Alien][Edited]
|
I'm building a live firing M41A Pulse Rifle from the movie Aliens, and I've acquired all of the parts to make it. I finally got my Thompson barrel off. This was a massive pain in the ass and took a while because I wound up having to cut the entire front sight off using a hacksaw since the taper pin would NOT budge. Would have had it done sooner, but I was waiting on the barrel removal tool and also had to deal with a move into a new apartment. I also wound up having to slot two of the screws to the rear sight, because the factory rear sight screws were soft and immediately stripped while trying to remove them. I can finally send the barrel off to ADCO to have it chopped, threaded for my Rugged Obsidian .45 suppressor, and reprofiled (likely won't be done until February though). It's a heavy bitch even with the aluminum receiver, shotgun barrel removed, and 3D printed barrel (threads aren't compatible with the real receiver though). After I finish the live firing 10 hole version, I might have to build an 8 hole version around a metal airsoft gun, airsoft 870/SPAS 12, and the spare metal parts I have. Things left to do to finish the 10 hole live firing Pulse Rifle build though:
You can see the extended charging handle compared to the factory charging handle, which will make working the bolt much more user friendly with the shrouds attached. Also pictured in the last picture is an Elysium ChemRail that I need to finish painting and glue together.      |
| That is cool. Can't wait to see a video of it shooting. Dub over it with the aliens sound effects. |
"Your enemy is never a villain in his own eyes. Keep this in mind; it may offer a way to make him your friend. If not, you can kill him without hate — and quickly." -Heinlein.
|
Originally Posted By RaptorFuel: That is cool. Can't wait to see a video of it shooting. Dub over it with the aliens sound effects. 
|
|
Update: I have cut the shotgun trigger group's trigger guard to fit the shotgun receiver. This was the final step I needed to do to figure out where to have ADCO cut/thread the barrel. They'll also be reprofiling it. The shotgun triggerguard indexes off of the plastic shroud. The SPAS 12 cage indexes off of the shotgun. The barrel vent indexes off of the SPAS 12 cage. The position of the shoulder for the threads on the barrel indexes off of the barrel vent support ring (needs to be in front of it). The shotgun barrel still needs to be shortened a bit more though. Shotgun also needs to be drilled out along with the handguard bracket/frame on the Thompson to attach the shotgun to it. I rendered the shotgun inoperable because I got the aluminum Thompson to save on weight and it will likely not hold up to shooting the shotgun even with low recoil rounds. I would hate to break my expensive Thompson receiver. It will still cycle and eject shells/dummy rounds, but it'll never be able to fire live shotgun shells. I need to have a small plate welded to the carrier/pump mechanism so that I can attach the pump handle/grip to it. I am not very happy with the barrel vent that I purchased. It's EXTREMELY heavy for one thing since it's made of 3mm thick steel tubing. It's ridiculously heavy and 10.5 oz in weight. You could beat somebody to death with it. It's also a bit over 1/4" too short and the tabs at the top terminate before they enter the shroud. I'll likely have a shop in China 3D print me a new one out of aluminum since I have accurate models. That will probably shave the weight down to 3oz or so. I've printed a couple of different ones out of PPA-CF, but it will probably still not hold up to the heat from the barrel let alone the muzzle near the suppressor. If I have a new barrel vent printed in aluminum, I will likely have a SPAS 12 cage printed in aluminum as well. Bronco Arms is coming out with as SPAS 12 replica and I plan to get one, but I may grab a second one to cannibalize the SPAS 12 cage from. I bought over a thousand rounds of .45ACP, but I still need to buy some 20 round mags and print a larger baseplate to fit my 30 round mag inside. I also need to fab up metal plates for the mag well and two metal fasteners for the rear of the shroud. I need to slightly widen the slots in the top of the shoulder stock so it can slide along the 4 rear sight screws on stop of the Thompson. I also need to drill out a recess for a detent and holes in the stock to lock with the detent so that it has adjustments like an M4 stock. I need to reprint the shrouds in PPA or high temp PLA as I'll likely not use PPA-CF. I have a digital counter but need to break it out and wire it up as well. Once all of that is done, I'll be sending all of the parts off to have them cerakoted or professionally painted. Nearly assembled with the plastic barrel.  Mockup with my Obsidian .45 suppressor over the plastic barrel.  Thompson barrel attached showing where I'll be marking it for the shoulder on the left side of the gorilla tape though I'll likely move it out towards the muzzle a millimeter more.    |
|
Not much to update on actual progress to the Pulse Rifle. The picture below shows a 3D printed barrel, but I finally took the final measurements to have the real Thompson M1 barrel modified by Adco by chopping/threading it, turning it down to reprofile/make it skinnier, and adding flats to allow it to be reattached using a crescent wrench. I'm sending it off today. The shotgun/grenade launcher is able to cycle dummy rounds but I permanently deactivated it so it cannot be made to fire to avoid damaging the aluminum Thompson receiver. The SPAS 12 pump handle is connected to the pump mechanism of the 870 via a welded plate and it works, though the guy that slotted the SPAS 12 cage made it too wide so the plate kind of rubs on the slot. I'm either going to have him add/weld a bead to the plate or I'll put a line of JB weld to widen it so it doesn't pop into the slot and cause excessive friction. I also received my replacement chamber heater for my 3D printer, so I'm going to finally able to start printing the shrouds in PPA for strength and temperature tolerance. I'm also going to print new magazine basepads for my Thompson mags, but I need to resize them slightly first in CAD before I print them. I also need to make a couple of minor adjustments to the shrouds in CAD. I bought larger counter sunk machine screws to connect the shotgun to the Thompson's bracket under the barrel along with proper counter sunk drill bits and taps. I'll be redoing this connection tonight or tomorrow. I'm going to place an order for a replacement 10 hole barrel vent 3D printed in aluminum from a company in China. Once the barrel comes back from ADCO, technically the gun will be functional. It'll just need final painting, and I'm likely going to Cerakote all of the metal parts  
|
|
Originally Posted By Deerhurst: Lage has one with a M11 in it. I definitely plan to pickup an FRT for the Thompson though.
|