Aliens M40 Grenade

The multi-purpose M40 grenades are standard issue for the Colonial Marines in James Cameron's Aliens. They could be detonated manually by removing the cap and pressing the timer button, or launched from the iconic M41A pulse rifle. The machined design made this the perfect first project for my new lathe.

The grenade was turned from a length of aluminium rod. For simplicity, I opted to make the cap part of the main body. Several people have asked how I made the ribbed section. This was done by first setting up my dial indicator touching a tooth of one of the thread-cutting gears, then using this as an index, manually rotating the chuck for each groove until the indicator zeroed. Each groove was made with an unpowered pass using a V-shaped tool, with the slide set at an angle.

I primed and painted the cap section. Despite having cut a shallow channel in the right spot to make it easier, painting the white stripe proved unsatisfactory, so I instead cut and applied strip of PVC tape.

The M41A pulse rifle props in the film were made by grafting a Remington shotgun onto a Thompson sub machine gun using a SPAS shotgun cage. The shotgun portion represented the grenade launcher. This particular m40 grenade was made at a slightly reduced scale so as to replace the dummy shotgun cartridge in the chamber of my pulse rifle replica. It would be nice to be able replicate loading grenades into the magazine via the bottom of the SPAS cage, but there is very little spare room inside the replica. My next customisation is instead likely to be improving the look of the Remington chamber and bolt with the addition of an extractor claw.