ARMAT M41A PULSE RIFLE

https://avp.fandom.com/wiki/M41A_Pulse_Rifle

"I wanna introduce you to a personal friend of mine. This is an M41A Pulse Rifle. Ten millimeter, with over-and-under thirty millimeter pump action grenade launcher."
―Cpl. Hicks, to Ripley (from Aliens)

The Armat M41A Pulse Rifle is a pulse-action assault rifle chambered for 10×24mm Caseless ammunition. It was notably employed by the United States Colonial Marine Corps and the United States Army as their primary infantry weapon during the late 22nd century. Through its use with the USCM, it saw regular use in various engagements with the Xenomorph and Yautja species.