The thing is, the video doesn’t support that claim, and points to another cheaper, less accurate rifle instead.
This rifle is a cheap Chinese knock-off… literally. The Chinese M99 featured in the video features a distinctive flattened boxy muzzle brake far different than the round brake of the AS-50, and the M99 lacks the forward Picatinney rail of of the AS-50.
The M99 shoots shoots about 2 MOA (minute of angle), which isn’t impressive for a sniper rifle.
Part of me doubts that this is even a real M99 (though I may be quite wrong). Why?
The shooter has no eye relief (his nose is alongside the scope body), and while there are excellent brakes on the market, I find it hard to believe that a .50 BMG or the Russian 12.7 can be tamed to have almost zero recoil, which is about what it would take to keep him from having a very bloody scope tattoo like this guy or this guy.
The video also shows that the weapon has a massive wall beside the brake, suggesting that the muzzle blast would be punishing to the shooter and those directly behind him, who hardly flinch when the rifle goes off.
Could this be a smaller-caliber trainer variant in 7.62x54R, or a similar smaller caliber?