doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Why doesn't this barrel blow up?

A pipe nipple breech plug, no safety glasses, this is quite dangerous. As mentioned, with all the slack in the fit of the barrel into the breech section, probably a lot of pressure is lost. Plumbing fittings belong under the sink, not in firearms. He has been lucky so far. I had a 12 bore burst 10 inches from the breech when I was shooting it and I don't wish that on anyone. The kid is lucky that he got no barrel burst from shooting out the obstruction in the bore and I am curious if there is any bulging. This kid is an accident waiting to happen.

Eightbore, you sound like my Dad. He never chewed me out when he discovered my home-made 12 gauge. It just disappeared and I found a brand new 12 gauge Winchester Model 37 waiting for me at the start of pheasant season.

Steve

Such slam fire guns have been made with ordnance steel and featured in other youtube videos. A production model made in the USA in the 1940s is also shown.

The fascinating thing is how these open, unlocked, systems behave during firing. Personally I find it interesting that both "barrel" and "breech" recoil together even though they are not mechanically connected.

There is also a vid showing the detonation of a cartridge in an open 12g barrel. It is evident there too that the barrel recoils together with the shell. The shell is not blown out of the open barrel as one would expect after reading the "authorities".

Such things get you thinking.

Perhaps a shotshell actually behaves as we have always been told a brass cartridge does, i.e., that is enlarges upon firing and grips the chamber wall, thus preventing it from having as much rearward thrust. I was told for years that they do not, but if the video shows it remaining in the open chamber during firing, it must. What else would hold it in there?

The brass imprints that we see on the face of the standing breech may be simply caused by the enlarging of the head of the shotshell against the breech, and not so much by a rearward motion against it. Brass cartridges expand, then retract to closer to their unfired dimensions, thus allowing ejection. Maybe a shotshell acts the same way?

Very interesting.

SRH

Let's look at what we know &what we can with reasonable safety assume.
We know that we have two tubes, one fitting inside the other. We know that one tube is open on both ends (the Barrel).
i think it sfe to assume the other tube is sealed solidly on the rear end with a fixed firing pin in the center.
thus when the inner tube is pulled forcibly enough to the rear to ignite the primer the gun fires.
now the solid end of the outer tube is fixed solidly to the stock which is supported by the firs shoulder. Thus the hull is not going to "Jump" out he back of the barrel as it is solidly supported from the rear.
.the real question then is why doesn't the barrel move forward off the hull from friction of the load going down the barrel. I think the answer here is the firer has just pulled it forcibly to the rear & still has a firm grip on it. Also as the barrel is large enough to accept the head of the shell it does not have a tight fit with the wadding. No doubt there is blow by & the load does not acquire full velocity. With the combination of these factors I think there is simply not enough force to blow the barrel forward. I do not see this in any way disproving that a shell has "Back Thrust" when fired. Obviously some classes of shells do have back thrust as .22RF, .25, .32 .380 ACP, 9mm Mak, 9mm Parabellum & .45ACP have all been used successfully in "Blow Back" designs. If there were no "Back Thrust" a blow back simply would not operate.
I do not know of anyone either repealing or amending the law that for every action there is an equal & opposite reaction.
Anyone who thinks there is no back thrust involved simply find you an old 870 Rem, remove the locking lug from the bolt, reassemble it, load her up & "Fire At Will". Prove the rest of the World Wrong, IF You Dare.

Stan has some interesting observations regarding the friction component of the shell in the chamber.

Considering the obvious markings of the barrel walls on the standing breech of some shotguns, I would say they are evidence that barrels and breech meet with enough force to make those imprints. Is it because the barrels thrust back, or the breech springs forward from the flexing?

Re the blowback force. Some auto pistols used a blow forward action. They can be seen in videos posted by the forgotten weapons people on youtube. Another one of those perplexing things about firearms.

And lastly there is that video of the open Mossberg barrel recoiling together with the shell. Fascinating footage. The shell has not thrust back from the chamber even though there is no bolt to hold it in. The barrel and shell recoil together.

Obviously these phenomena contradict the gospel. A closer, more scientific look might be worth doing, and might explain why break open designs shoot loose. The cause could turn out to be something unexpected.

It seems I remember an early Winchester auto nicknamed "The Widowmaker" where the entire barrel slid back during the ejection cycle.

Steve

Steve,

That is the M 1911 S.L. (self loader), called the "WidowMaker" because it has no handle on the bolt to pull it back and unload the chamber. You have to pull back on the barrel to eject the live round from the chamber, and some careless souls would put the butt on the ground and push down on the muzzle to do so.

SRH

Stan's got it right. I used to shoot one of them. The barrel end was knurled/checkered to form a grip to pull or push the barrel down in order to open the action or unload. Scary...Geo

The Win 1911, as was the Browning A-5, were Long Recoil operated arms. On these the bolt & barrel, locked together, recoil to the end of their cycle together. The bolt is held the barrel unlocked to go back forward at which point the bolt is released to come forward, picking up a fresh shell on the way.
I will probably miss a few but full & semi autos have been made on the long recoil, short recoil, gas, blow back, delayed blow back, blow forward, primer actuated & a few others I can't recall off hand. Julian Hatcher in Hatcher's notebook covers most of them.

When powder is ignited in a closed container it gives equal pressure in all directions. For a cartridge case to stay in the chamber with no support certain criteria must be met. The case must expand & grip the chamber walls tight enough to resist the backward thrust. There is absolutely no doubt this thrust exists. Also the construction of the case must be stout enough the case head will not separate & be Blown Off.

Anyone is of course free to do as they please, but personally want my guns constructed on the premise they must be able to resist a considerable Back thrust from the case on firing. Over the years there have been too many cracked frames, oo many guns declared to have breeching too weak to handle heavier loads for me to believe otherwise. Among shotguns the 1893 Win & early Marlin pumps come to mind & among rifles the "Trapdoor" Springfield & toggle link Winchesters. The barrels on these were not declared unsuitable but the bolt support was.