This short clip is equally hilarious and terrifying.
I have often wonder how recoil is absorbed. I had assumed the seat and mount had shock absorbers.
Apparently not. 
Wait a minute. Where’s the swivel seat that he should be strapped into?
No wonder he was tossed like a rag doll.
Btw, a small phone screen won’t show much detail. Need to press the lower right corner (double headed arrow) and Go into full screen.
It’s supposed to be mounted on a helicopter, not free spinning on a post in the ground.
Something like this:
Shouldn’t the gun also be mounted on the axis, so it doesn’t generate any torque?
Yes.
You most often see machine guns mounted off-axis on improvised weapons where they don’t really have a proper mount for the gun.
WWI biplanes often had the machine gun mounted on the upper wing, above the pilot. It’s not necessarily the best position for the gun from a shooting point of view, but wing-mounted machine guns would generate enough torque on a light biplane to spin it around and cause issues with flight control. Once they figured out how to tie the propeller’s rotation into the machine gun with an interrupter mechanism, then they could move the gun down into a better firing position. But the machine gun was still kept in line with the plane’s fuselage.
WW2 fighters had wing-mounted guns but pulling the trigger fired the left and right guns simultaneously, so torque on the plane wasn’t an issue.
The same concept also applies to smaller weapons. For example, the recoil forces on an AK-47 rifle are not straight back into the stock (mostly due to the charging handle on the right side of the weapon, IIRC). As a result, when you fire an AK-47 it tends to climb up and to the right, making it difficult to stay on target when firing in full auto mode. A lot of modern assault rifles have a muzzle brake or compensator that intentionally vents the barrel gases upward to stop the rifle from climbing when fired in full auto (also helps keep the weapon on target for the next shot in single shot mode). You even find ported barrels on some pistols that accomplishes the same thing.
Yes, it should, that was my take when I saw this on reddit a few days ago.
It seems clear they were trying to balance the gun on one side with the ammo carrier on the other, and never stopped to think about torque around that axis. Sheer incompetence.
Maybe he was practicing being surrounded.
It looks like the gun can only shoot straight or upwards to the sky.
If that truck is 7ft tall then the gun might shoot over the heads of any troops walking on the ground.
Certainly troops in fox holes would be safe.
Right, this is not the kind of weapon you just casually slap on top of a pintle designed for (the Russian equivalent of) a .50-cal or single barrel 20mm and just leave free-floating for one man to hold on target. At best, someone failed to tighten several somethings. (And we know they’re not at their best.)
Points though for the splendid yeet of the gunner.
In the full clip once the spin slows down a bit, the other crew member reaches up to stop it and when he cannot get enough leverage from the ammo box just goes to grab the barrel and immediately discovers that was not a good idea.
I think “stop” is a bit aspirational there. “Slow” is about the best that can be said for the effects of muzzle brakes/compensators on most guns.
But yeah, clearly the recoil and whatever gyroscopic forces are caused by the multi-barrel action go straight into spinning the mount around. That’s quite a bit of force to yeet a person bodily the way it did.
Doesn’t strike me that they put a lot of thought into their mount, and this was more of a “Boris, hold my vodka!” type mounting.
Heh, reinventing the “technical” but did not bother to go online to ask some actual African guerilla fighter for pointers? “Bush fighters put AA gun in back of Toyota, in cave! How hard can it be?”
Another possibility. he’s training so when he goes on Carousel, he’ll be certain to Renew.
Last night, I read they produce 1400 kilograms-force of recoil at full BRRRT. You could ride it like a rocket, briefly.
I wonder if the guy behind him who had to duck was pissed off at him.