Anthem

All of the Weapon I Challenge achievements are quite similar. For this one, you need to kill a total of 50 enemies with 3 different variants of the light machine pistol.

You can track your progress by pressing , then browse to Challenges -> Weapons -> Machine Pistol. Select the rifle you want to track and hit .

The machine pistol challenges required for this achievement are:

Fulcrum I
Hailstorm I
Trajector I

Basically, any mob can drop them. You will also get it off treasure chests and other mission rewards.

Colossus javelins are the only class that can't equip the machine pistol. Thanks to Lord Von Chimp for the update.

EDIT: AS of 3/9/2019, this achievement is buggy and will not unlock for some poeple. No workaround is known. Hopefully, it'll get patched soon.

There are three machine pistols in Anthem, and for this achievement, you'll need to get 50 kills with each. You can see your progress by pressing , then over to Challenges, scroll down to weapons and then to machine pistols. Sometimes, you'll need to press twice, then to get the game to show all the challenges available. For the first challenges, all enemies count the same, so focus on the weakest enemies available.

You'll want to make sure that the weapon you are using is close in power level to the rest of your gear. Any newly collected or crafted weapon will do. It can be hard to get a specific weapon to drop. You may just have to keep killing bosses and replaying missions until you get the weapon you need.

All three machine pistols function like SMGs in other games. Medium magazines, high rate of fire, medium accuracy, high recoil. If you are having trouble getting kills with a specific one, take it into freeplay, and kill some wildlife. Bring a scout rifle for backup. Also, note that the colossus cannot equip machine pistols.