bushmaster1313
Member
Handguns seem to work just fine on the blowback principle.
Why not a blowback .223?
Why not a blowback .223?
So what keeps the bolt from blowing back on an AR-15?
The locking lugs on the bolt.So what keeps the bolt from blowing back on an AR-15?
So what keeps the bolt from blowing back on an AR-15?
When a round is chambered, the bolt is locked to the barrel extension and force on the breechface can't unlock it because the bolt lugs have rotated to engage matching lugs on the barrel extension.
The gas pressure routed back to the bolt pushes the bolt carrier back which causes the bolt to rotate and the lugs to disengage from the barrel extension.
The bolt is blown back, but by gas pressure bled from the barrel routed through the gas tube, not by force against the breechface as would occur in a blowback design.
The critical difference is that the breech is locked closed and can't be opened by force against the breechface. In a blowback, the only thing holding the action closed is the inertia of the bolt/slide and the force of the recoil spring.
Handguns seem to work just fine on the blowback principle.
Why not a blowback .223?
Well a .223 blowback gun is not necessarily impractical. Look at the HK33 or even the G3 which fires the .308. Those are blowback operated guns.
Granted it's a roller-delayed blowback and not just a straight blowback design like your typical SMG. But blowback none the less. I hear they tend to beat the hell out of your brass because of the pretty violent ejection unlike the softer gas operated designs. But for a military rifle that's hardly important. Not like you have soldiers scouring the field after battle to pick up the brass.
Utilizing recoil force to unlock and cycle the action is not the same as a shell case pushing back into the bolt. They are 2 distinct operating systems. Or maybe blow back is a fancy term for non-locking recoil operation.68wj, recoil-operated is just a fancy way of saying "delayed blowback". It's still a blowback, just one with a semi-locking breech to reduce the slide impulse.
The mechanisms and operation is completely different between blowback and delayed blowback. That's why we differentiate between the two by adding the adjective "delayed" to the latter.Well a .223 blowback gun is not necessarily impractical. Look at the HK33 or even the G3 which fires the .308. Those are blowback operated guns.
Granted it's a roller-delayed blowback and not just a straight blowback design like your typical SMG. But blowback none the less.
The recoil from the gun moves the bolt-carrier backward, unlocking the rollers. Once the rollers are no longer locking the bolt tot he breech, then the cartridge pushes back the bolt like in a regular blowback gun.
68wj, recoil-operated is just a fancy way of saying "delayed blowback". It's still a blowback, just one with a semi-locking breech to reduce the slide impulse.