Call of Duty YouTuber calculates that these Black Ops six barrels barely do any thing

This is not good news for Black Ops 6 Gunsmith. TheXclusiveAce, a helpful CoD YouTuber, recently published a breakdown on Blops 6 barrel attachments. He found that, amazingly, most of them were essentially useless.

I wish it was an exaggeration but the math is correct: CoD's ballistics model allows most guns to be hit-scan up to 30-40 meters. The game doesn't mention this element of its gunplay, even though 30-40 meters is longer in Blops than 90% of gunfights. Increasing velocity with the Gain Twist Barrel is largely pointless. Long Barrel is also a good option. With the exception aggressive SMG damage dropoff, the default damage on Blops 6 guns are so forgiving that it's unlikely you will notice a difference in time to kill. The third barrel option is the Reinforced Barrels, which increases both range and velocity. You can also ignore that one for most situations.

The only two options are the CHF Barrel, which increases headshots damage. However, this is only useful in certain situations and depends on the gun. Extra headshots damage does not always mean that it will take fewer shots to get the job done. This is a lesson that has been true in the last few CoDs: you should focus on attachments that enhance the gun's handling (like grips and underbarrels) and ignore ballistics.

Why are there prominent attachments in Black Ops 6 that do nothing? It could have been a simple mistake, but it's more likely that Treyarch designed these barrel attachments not for Blops 6, but for Warzone. With its large maps and long gunfights, you need the most potent combination of velocity/range for all of your weapons.

The game doesn't tell you that. You have to look at the statistics to realize that the green arrows that are going up don't help you. This is counterintuitive to a system designed to make your guns more interesting or better. This sort of bad design would be laughed at if this was any other series. Unfortunately, the best-selling series is still doing business as usual.
This week, you'll have the chance to use Blops barrels in their intended purpose. Black Ops 6 Season 1 starts on November 14. Warzone will be integrated into the Blops 6 fold along with Omnimovement, and a Resurgence map called Area 99.