Sometimes, despite having the necessary mods, they will not be able to be applied to the weapon.
The 12.7mm SMG is almost entirely fictional, though a couple of elements were loosely inspired by the FN P90 and TDI Vector. The GRA version of the silencer (suppressor) on this weapon is not interchangeable with the one for the standard version silencer.
Sold by various merchants around the Mojave Wasteland.
Durability (number of attacks before breaking) Damage per attack (damage per projectile)
12.7mm submachine gun - the common variant found in the Mojave Wasteland. I really, really wanted to use the 10mm silenced or the 12.7mm silenced but I still haven't found a 12.7mm pistol or 10mm silencer.
12.7mm submachine gun suppressor - silences the weapon.
12.7mm submachine gun stacked magazine - increases ammunition capacity by 6 rounds, from 21 to 27.
12.7mm submachine gun laser sight - decreases spread by 0.4 (from 2 to 1.6).
The 12.7mm submachine gun (GRA) can fire a total of about 2,495 standard rounds, the equivalent of 119 reloads, or 93 reloads when modified with stacked magazines, from full condition before breaking. This weapon has more weapon modifications available to it than the standard version.