doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Barrel wall thickness

UK Working Standards recomended minimum wall thickness measured 18" from the barrel breech from Double Gun Classics p. 56, Vol. 1, No. 4 Jan-Feb, 2006:
2 1/2" 12g - .028
2 3/4" 12g - .032
Re-proof recomended minimum - .024

The Hunter's Encyclopedia - from the German proof house: minimal wall thickness at the end of chamber, regardless of length, for 12, 16 & 20 gauge guns should be 2.3mm (.0906") for 'Ordinary Good Steel' or 2.1mm (.0827") if a 'Special Steel' was used.
For the 24 & 28 gauges, due to their higher pressures, 2.4mm (.0945") was recommended.
Minimal wall of .6mm (.0236") was recomended in the "forward third" of the barrel.

A bit more from the 1933 Dupont booklet.

Note they are using lead crushers. They do show some oscilloscope images.

It reminds me of reading P.O. Ackley discussing how to make a pendulum to measure velocity...



They do discuss barrel wall thickness. But for them, it is a question of design.

Essentially saying that a gun designer assumes the pressures of known powders.

Please note, when they talk about barrels they start by talking about artillery, then rifles and finally shotguns.





Pete

The authors of the example in this reprint are somewhat mistaken in that what he refers to as total pressure is actually force. Force = Pressure X Area. The pressure of 10,000 psi is exerted equally on all parts of the cylinder, and in a shotgun, begins dropping quickly as the charge moves down the barrel.

I'm certainly no expert, but on SGW, the question came up about pressure and the super speed steel loads of 1700 FPs.
Best I remember, one guy's information from Remington was it was a two stage ignition. The second stage was a nano second behind the first; both peaks were still in the chamber.