M6J/C carbine

The M6J Carbine is a United Nations Space Command infantry firearm.

It is the carbine variant of the M6 Series of sidearms made by Misriah Armory, and is used by the UNSC Army

Trivia

 * A carbine, in pistol terms, is a sidearm, with an attached stock. It's most likely, that the M6J is similar to an M6D, with an additional stock and barrel to increase its size to that of a carbine weapon and its dead mass (thus reducing an active recoil) and to allow more precise aiming.