The Task Force Barrel is a very unique attachment because it has different stat changes depending on what type of gun you use it for. It is available at any level for all gun classes. For most gun classes, each gun gets improved damage (3%-45%), effective damage range (40%-100%), and bullet velocity stats (50%-120%). Shotguns (Hauer 77 and Gallo SA12) only benefit from increased damage, but the increase is much higher than most weapons in other gun classes; 45% for the Hauer and 81% for the Gallo.
However, you should be aware that some stats take a hit with this attachment. For assault rifles, SMG’s, and pistols, max starting ammo (25%-33%), vertical recoil control (20%-30%), and horizontal recoil control (15%-20%) all decrease. For tactical rifles, only vertical recoil control (20%) and horizontal recoil control (15%) are decreased. LMG’s have decreased magazine ammo capacity (7%), max starting ammo (38%), and ammo capacity (7%). In shotguns, only the effective damage range (13%) is affected. You’ll notice, however, are mostly outweighed by the benefits.