doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com black powder shotgun pressures

Pete;
I note that Cox's original chart has 5 powders listed, while the Rifleman version shows only 4. As curve A in Cox's goes above 10K it obviously is the powder not listed in the Rifleman chart. Can you supply the name of that powder?
Note also that the black powder pressure is exactly 9K, while higher than most associate with black it does not reach 10K.

Miller,

No problem, for you...

From the text on page 20;
Curve A - representative of the characteristic pressure curve developed by a double-base or nitroglycerine powder such as Ballistic.
Curve B - Dense Multi Base Powder, DuPont MX Smokeless.
Curve C - Bulk Nitrocellulose Powder, DuPont Bulk Smokeless.
Curve D - Black Powder
Curve E - Progressive Burning Nitrocellulose Powder, DuPont Oval Smokeless.

He states that the curves have been smoothed or cleaned up from the actual oscilloscope data. Also they have further been "adjusted" for publication.

My copy came from the library of Max Thompson, a Winchester-Western Ammunition product service manager in the early 1960's.

Pete

Thanks Pete;
DuPont MX, Oval & Bulk Shotgun were still listed in a 1950 Lyman manual. Bulk is listed as suitable for 3-3½ dram measures with from 1-1¼oz of shot. MX is given only in a 3 DE loading (25.5 grains) for 1-1¼oz of shot, while Oval is recommended "Only" for a "Max" load of 40 grains with 1¼oz shot. It was noted in the Rifleman article that this 3 DE loading of Oval was in fact an "Underload" for that powder. It is noted from the charts that while this powder did give the lowest peak pressure it also had a quite high pressure at around the 4" point. It is well to note that these test were run with all of the powders being loaded to give essentially identical ballistics to the same wt of shot. This was seemingly done to provide a showing of the requisite presure curves developed & not a blanket recommendition of the loads. The load of Ballistite was certainly pushing the envelope from one end while that load of Oval was one which would have been subject to failure under many field conditions, especially for the cold weather use it would have been most apt to be used in, as a waterfowling load. The Lyman manual recommended against its use for anything other than obtaining maximum velocity with the 1¼oz shot load (12ga).
I am still a firm believer in using powders under shot loads for which they were designed, keeping presures reasonable by limiting the total balistics of the load, & forgetting all these "Super Low" pressures using loads for which the powders were not designed.

Miller,

I found it interesting that they were using oscilliscope data for their charts. Which means some one was sitting there ready to press a shutter, then had to run out and have the film developed. So the "smoothing" was most likely done to give the data a little more regularity.

Apparently they made some changes for the 1950's article, not surprising. Later, he cites a formula, which he calls Torricelli's Law used to calculate hydrostatic pressures to burst a barrel.

Pete

PeteM
what does tha thave to do with black powder??

Not PeteM but if you look the chart over closely, you will see one of the curves was run for Black POowder. That's what it has to do with BP. Pete ran the chart in responce to my having stated the pressure black had generated in this test. Thanks for the Chart Pete. I had never had opportunity of seeing that top Ballistite curve. I knew that a 5th curve had been generated in the original, but did not know where it fell or with what powder it was taken.

I am still a bit confused. I always thought that Black Powered loads operatated in the 5000 to 6000 range, more like the second example. I assume we are talking 12 ga.

Perhaps the old BP was remarkably stout.

Thanks for the info guys

Thanks a lot fellas. forgive ma for not being able to read the fine orint. You have been lots of help

RPr,

Confusion comes with the territory on this one. Coxe never states how much FFFG he used. At 9,000 psi, they were duplicating many of the old black powder proof house loads. These were for max pressures rather than service pressures.

What is interesting is how quickly some of the other powders shed their pressure when compared to black powder.

The loads I quoted above from the Lyman book are actual working service loads.

Pete

PeteM;
In the Rifleman article all (4) loads are stated to have been a 3-1¼-7½ load. Thus 3 dram wt of black, 3 dram measure of bulk & a 3 Dram Equivelent of the smokeless. Was this not stated anywhere in Coxe's data. I "Assumed" the Rifleman author had gleaned this from the original data. This would have been a service load & not a proof one at this level.
In fact heavier loads are listed in the 1913 Lefever Arms Co catalog for Ballistite, DuPont Bulk & Black, I don't think MX & Oval were around yet at that point in time.