Re: Powder pressure curves
Posted by Drew Hause on October 8, 2017, 8:48 am, in reply to "Re: Powder pressure curves"
Coxe did not share the grains of black powder used to generate the pressure curve; but it was likely proof load. The intent was to demonstrate, at similar pressures, that the pressure curves were also similar; black powder (in a shotgun shell) was neither an explosive nor a slow burning powder. |
Here's another from "Smokeless Shotgun Powders: Their Development, Composition and Ballistic Characteristics", 1931. NOTE: "All powders loaded to develop the same energy" (ie. the area underneath each curve). The curves essentially meet at 3 1/2".
1 1/8 oz. 3 Drams (1200 fps) of DuPont FFFg (82 grains) is about 5000 psi.
1 1/8 oz. 3 Drams Curtis & Harvey’s No. 4, T.S. (82 grains; somewhat similar but not equivalent to medium grain FFg) was about 6500 psi.
1 1/8 oz. with 100 gr. GOEX FFg at 1200 fps = 4,800 psi
1 1/8 oz. with 100 gr. Pyrodex RS at 1200 fps = 5,600 psi
1 1/8 oz. 3 Dram Equivalent of BULK Smokeless was 6500 - 7500 psi.
1 1/8 oz. 3 Dr. Eq. of DENSE Smokeless was 8,500 - 10,000 psi.
Most (non-obstruction) barrel burst occurred after the introduction of DENSE smokeless powders, which were loaded by the unknowing or careless using volumetric scales designed for Black Powder or BULK smokeless powder, rather than by weight.
A 3 Dr. Eq. (Dram Equivalent) load of “E.C.” No. 1 or “Schultze” was 42 grains by weight. 3 Dr. Eq. of Dense Smokeless Ballistite was 24 grains; "Infallible" 22 grains.
Substituting a Dense Smokeless powder for Black or Bulk Smokeless powder would double the charge. It has been estimated that 50 grains of "Infallible" or Unique could reach 30,000 psi.
Sporting Life Sept. 10, 1904
“Burst Gun Barrels”
The number of burst gun-barrels which, comes to the attention of the shooting public is remarkably small, considering the thousands of guns in use throughout the country. The main reason for the comparatively small number of guns burst is the great use of factory-loaded shells, or the hand-loaded of reliable dealers. The day of loading one’s own shells is pretty well passed, therefore, the over-loaded or double-charged cartridge is very seldom found. Very often a burst barrel is blamed on the gunmaker or the shell-maker, but more often on the manufacturer of the powder. Cases are known where a party blowing out a gun-barrel, using an extra heavy charge of dense powder, blamed it on a bulk powder. A suit for damages was quickly withdrawn after an examination of the gun had been made.