Alien Ammo

Perhaps the most important thing to control for reliable operation of the Alien pistol is the ammunition used. Because of the gas system that delays blowback, the wrong ammo will lead to unnecessary buildup and finally, failure to cycle the slide.

The gun was designed around Sellier & Bellot 124gr FMJ ammunition; so that’s a good place for most people to start. But as good as that ammo is, the bottom of the bullet still has exposed lead. And lead in the gas cylinder is deadly for performance. If you reload your own ammo, you can step up to a bullet that is fully enclosed such as Delta Precision 124gr JHP, Everglades 124gr JHP RN, or Montana Gold 124gr CMJ.

While you’re reloading, be sure to use the cleanest burning power you can. The nature of the gas system means that there will be a lot of powder residue inside the gun – might as well keep that as low as possible. Vihtavuori N320 is well known for its clean burning as is Winchester 231.

Keep in mind that some chamber gas is used for the recoil system, so you’ll need a little more powder than you may be using now to make your target power factor.

Another consideration is the bullet’s ogive (shape). Round nose, just like the S&B FMJ bullet, may be best. But JHP can work, too, if the overall length (OAL) is ‘right.’ S&B 115gr FMJ OAL is 1.160". JHP, such as from Precision Delta, needs to be shorter; I’ve found that 1.100" works for me.