doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com ammo pressure question

Pete, Miller,
Thanks. Yes, now I recall this chart. Yes, the "area under the curve" or total energy has to equate if the same velocity is achieved for same wt payloads. That 10" point on the chart is probably more or less close to a gas port on a gas gun. Looks like D. Oval is about 1500 psi higher than A. MX at the 4" point.

One thing I did find for myself, is that all promo loads don't necessarily have SAAMI max pressures. I tested several loads over two gauges and never got a max pressure or even within 10% of max. The pressure rig was verified with a known pressure load.

ANSI/SAAMI Shotgun Pressure Specifications (Maximum Average Pressure in PSI) All Piezo measurements unless specified

Cartridge Maximum Average pressure
10 gauge 11,000 (all)
12 gauge 11,5000 (all but 3 1/2" mag)
12 gauge 3 1/2" mag 14,000
16 gauge (11,500 (all)
20 Gauge 12,000 (all)
28 gauge 12,500 (all)
.410 Bore 2 1/2" 12,500
.410 Bore 3" 13,500

Cartridge Class Shotshell
Multiply Max Average Working pressure by
Minimum Proof* 1.55
Maximum Proof** 1.70

* Min Proof values rounded UP to nearest 500 psi.
** Max Proof values rounded DOWN to nearest 500 psi.

Pete

Pete,

Do you know the approximate date when DuPont ran these tests?

Rich

Rich,

I really do not remember.

Miller do you recall when this was 1st published.

Pete

Just looking at the text below the table it seems to indicate the loadings were 3" 1 1/4 oz 7 1/2 shot. So, that would put it post 3" mag timeframe. '30s/40's? Seems like Miller had the reference originally.

Chuck,

I read that as 3 drams (or DE) NOT as 3,0 inch hull.

Niklas

Good catch Niklas. Makes sense.

They name 3 DuPont powders:
DuPont MX
DuPont Bulk Shotgun smokeless
DuPont Oval smokeless

So, when were all 3 on the shelf?

Pete

Friends:

The chart was originally published in the handbook published by DuPont "Smokeless Shotgun Powders - Their development, Composition and Ballistic Characteristics as They Effect the Action of Your Shotgun" by Wallace E. Coxe, 1933.

Tidbits: Ballistite manufacture was discontinued in 1922 ( see page 13). MX Smokeless was introduced in 1933 ( ibid) .

The illustrated curve ( page 20) is produced by pistons, with the results "... corrected by results obtained by the (piezo-electric gauge and cathode-ray ) oscillograph..."( page 20).

The text also notes various tests conducted on several powders, such tests being conducted in January , 1933.

Pete- DuPont Oval, MX, and Bulk were all on the shelf in 1933.

Hope this is of interest.

Regards

GKT

Greg,

A true well of knowledge. I have broken the link for the former graphic. I made an addition to the chart, so I will not forget the source.



Pete