Author Topic: When does blowback happens???  (Read 472 times)

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Offline Practical Shooter

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When does blowback happens???
« on: June 11, 2019, 05:11:16 PM »
As seen on this video,  the "delayed blowback" was created to allow blowback to be put on hold until the bullet had time to leave the barrel, before any gun parts started to move.

But in this video, our two "Mythbusters" demonstrate that NO gun parts moves until the bullet is way out of the barrel.

So my question is .... does the "Delayed blowback" really worth it, or just a Myth?

Offline Tok36

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Re: When does blowback happens???
« Reply #1 on: June 11, 2019, 07:33:11 PM »
The pistol in the Mythbusters video is a 1911 with a Browning style tilting barrel action. Rather than a type of blow back it is a type of short recoil system (the barrel moves). One is a locked action while the other is an unlocked action. While i can not give you a definitive answer to your question it seams to me that the reference material used to formulate your question may not be applicable.

« Last Edit: June 11, 2019, 08:58:05 PM by Tok36 »
Will work for CZ pics! (including but not limited to all CZ clones)

Offline M1A4ME

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Re: When does blowback happens???
« Reply #2 on: June 11, 2019, 08:18:10 PM »
Blow back pistols/rifles, like a .22 semi auto, or the 9MM AR15 pistols/carbines with no locking system on the bolt will sometimes spit a tiny ember of still burning powder out of the ejection port when the bolt moves to the rear.  If you're standing off to the right side of the shooter, looking at the gun, you can see it.  Sometimes you can see it, out of the corner of your eye, when you're shooting it.

Did I mention how dirty they get?  My AR15 pistol and carbine will come home with a noticeable dull black "finish" on the upper and lower in the vicinity of the ejection port.  If you touch that stuff your fingers come away blackened (powder residue that would go on out the muzzle if it had a locking system on the bolt like a .223 AR15) and they take some wiping/scrubbing to get them clean on the outside, let alone on the inside.
I stopped carrying the SIG 556R.  SIG changed models and couple/three times and stopped supporting it with parts.  So, I stopped supporting SIG.  Back to the tried/true AR15 Carbine.

Offline motorcyclist

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Re: When does blowback happens???
« Reply #3 on: June 12, 2019, 02:10:52 PM »
There's blowback operation, and delayed blowback. Simple blow back is most 22's like 10/22 Rugers, the new 9mm PC and lots of 380 pistols like CZ 82, Makarov and such. The mass of the slide (or bolt in a SMG or carbine) and the recoil spring keep the breech closed till the bullet has left the barrel.
Then there's delayed blowback. As Ian said, the gas delay systems he shows are pretty rare. Gas pressure is tapped from the barrel and trapped in a chamber forcing the slide forward, delaying breech opening. Far more common is roller delay. German engineers starting developing it around WWII. The most common I can think of would be the H&K MP5 SMG.
If you want to get into it there's also lever delayed action and a few others. Google "delayed blowback" and you can read for days.