Or ask someone who uses the damned things for a living.
Blanks require a plug at the end of the barrel so the bolt will cycle. That leads to all sorts of s**t flying back into the weapon's operating parts and tends to gum up the bolt pretty good. I mean, I've had a C7 so badly fouled by firing blanks (last time I borrow someone else's rifle when they need an extra body for OpFor in a hurry) that I had effectively a straight-pull bolt-action C7 and shortly thereafter I couldn't even manually #### it anymore. That's one gun I had to clear using some violence and that made it's way right to the plumbers the moment we got back in garrison.
And the problem in that video looks like a mag issue to me. Since he says the "router", which to me I think is the follower, is crooked, maybe it's an issue with the "clips" holding it against the spring being busted. But that's just my guess.
I figured that one who "uses a C7 for a living" would at least know what is going on with his weapon.
Blanks do not send any more
"blow back" than firing a live round, the BFA doesn't seal the barrel it just retards (much like the above comments and the user on the clip) the gas enough so that some can go down the gas tube and function the weapon, in effect taking the place of the bullet. You get more stoppages with blanks for 2 reasons:
#1. The blanks are shorter that live rounds and have a flat face compared to a bullet, the get hung up when being forced into the chamber causing maffunctions;
#2. Most idiots on the trigger do not bother to properly lube the weapon, or insist on firing blanks like an idiot burning off any lube, crap only builds up on a dry weapon.




















































