The 9mm C1 is described in the game as:
A Cold War veteran, still in use today
You’ll find this located in Remanzo province, north-east in Remanzo Base “An industrial area, now the cartel base in Remanzo”. A nearby mission “The Quinoa Factory” is in the base. The weapona case is in armoury in middle of the base.
My approach was to sneak in at night, take out the snipers, and disable the alarm and lights.
This gun has a side loaded magazine but only the scope can be changed in the gunsmith. The real gun has folding buttstock under the gun, but apparently not in Wildlands.
It’s full-auto only, no select fire. There’s no suppressor, it has a low rate of fire and a bit of recoil. It’s kind of a gun for fun – not really for tactical play. There’s a 34 round magazine, but no extended magazine option. The only other option is a long barrel, found in Pucara.