Recall of course... this video is a lie.
The video does not make sense on what happened.
How can the barrel Not move on the first two rounds, but moves forward on the 3 round.
That would not happen, factory rounds fall into chambers... undersized in all respects.
So the cartridge can not all the sudden push the barrel forward unless it's the wrong caliber cartridge for the rifle's chamber.
Unless the barrel extension does not align with bolt all of the sudden, the bolt pushing on the back of the barrel extension therefore the barrel forward ...(not noticing the extra force needed to chamber the round at this time).
The extractor most likely not engaged in the cartridge head, not enough pressure, that gap would be enough for the firing pin not to reach the primer with full force.
And if it did and detonation occurred the cartridge fired and blew off the bolt handle as stated...the bolt to barrel alignment and quality still seem to be a problem.
But there is the old gunsmith PO Ackley experiment of many years ago, if any care to look it up.
He took a 30-30 lever action pulled the locking lug, loaded a factory cartridge in a dry chamber and fired it with no locking bolt... nothing unusual happened.
Ackley states the pressure expands the brass against the chamber walls which holds the cartridge in place.
But this cartridge was not fully chambered, and the operator should have noticed.
Not a fan of this type of barrel attachment for general public use with high pressure center fire cartridges.
Its more of a short range James Bond, European, movie assassin type rifle.
I wouldn't own one....but you can.
Let's try it with some 80,000 psi hybrid cases.
