Wonder if Al has ever put shots downrange out of a Barrett....
No, not in semiauto mode.
I've fired the bolt action Barrett and an AR50 and even a 13lb McBro's Big 50.......I'm no expert on the BMG round but I do understand the concept of recoil and I stand by my contention. I contend that without a muzzle brake we'd see another flexural movement, that of the shooter leaving the frame!
Alla' that timing stuff is due to one thing, inertia. Hard to get 'er moving and hard to stop the movement but the brake definitely controls the recoil by catching the lump of exiting gas...... ain't much "rocket effect" left on the forward end, and no push after the brake IMO. Just because I don't advocate brakes doesn't mean I'm unfamiliar with them, I've got one of Benny Cooley's units setting on the lathe right now waiting to be bored out to .750 for a 338 Lapua Improved barrel.
BUT....... aside from all that. THERE'S NO SUCH THING AS GAS AHEAD OF THE MUZZLE PUSHING THE RIFLE BACK!! That gas is GONE, the recoil happened as you accelerated it up to vel. Want proof? Go into your shower, take down the flexible shower head dealie and turn it on. Hold it or hang it or set it on the handrail. Watch how it swings or slides because of the "rocket effect"..... Or go out to your garden hose, lock the head on "spray" and watch it rock back under pressure.
Now.... it's all rocked back/pressured up......... take your free hand and block the spray (you're gonna' get WET!) and move closer and closer to the sprayer head, try to "push" it further by pushing the water back.......
I'll agree that there's a very small rearward component generated when the leftover gas
in the barrel acellerates rapidly after the bullet's gone. This is because energy builds as the square of velocity and the velocity of the gas goes up rapidly when unconstrained by the bullet but it ain't much. IMO It doesn't account for the surge you see in the vid. Wanna' test this one? fireform some cases using only powder. I routinely fireform .308 sized cases using 40-50gr of shotgun powder. It shoots flames 20ft in the air, and recoils about like, oh, 40-50 grains
I contend that that tha'r Barrett has just ejected eight hunnerd-n-fiftysome grains of mass (gone) and the 30-50gr left in the barrel doesn't materially add to the recoil impulse. The real recoil comes from running an eighth of a pound up to 2700fps...... and that the surge noted is the result of the distribution of the original impulse, not from a "jet effect."
i could be wrong
al