Well this doesn't bode well for Black Ops 6's iteration of Gunsmith. Helpful CoD YouTuber TheXclusiveAce recently published a breakdown of Blops 6's barrel attachments and determined, amazingly, that most of them are essentially useless.
I wish that was an exaggeration, but the math checks out: Because of how CoD's ballistic model works, most guns are hitscan up to 30-40 meters. The game does not communicate that element of its gunplay anywhere, despite the fact that that 30-40 meters is longer than ~90% of gunfights in Blops, so increasing velocity with the Gain-Twist Barrel is mostly pointless. The same goes for the Long Barrel: With the exception of aggressive SMG damage falloff, the default damage range on Blops 6 guns is so forgiving that you're unlikely to notice a time-to-kill difference by using it. Considering the third barrel option, the Reinforced Barrel, just increases both velocity and range, you can forget about that one in most situations, too.
