Thought this might be of some interest. I started doing some shotshell tests Saturday using a cheap NEF 12 gauge shotgun outfitted with a strain gage for the Oehler M43.

These first loads tested are my more or less standard 12 gauge target and light field load. All velocities are instrumental at 6 feet. The temperature around noon here in SW Oklahoma on the day of the test was 62� F., winds calm, 39% RH, bright and sunny. The charge bar is the standard MEC 502/118.

As a check, I verified the M43 recorded velocities with the M35P. (As an aside, it isn't much fun shooting 60 rounds of even target-type ammo through that NEF in an afternoon. Thank goodness for my sissy pad!)


Test #1:
Winchester AA once-fired hulls (old 1-piece style)
19 grs. Red Dot
Winchester WAA12 wad
Winchester 209 Primer
1-1/8 ounces of #7-1/2 shot
Sample size = 10

Average velocity was 1168 fps @ 8,100 psi. Velocity standard deviation was 10 fps, pressure standard deviation was 400 psi.

Test #2:

Sample size = 9 (first shot failed to record)

Same as above except I used Remington STS once-fired hulls. Average velocity was 1176 fps @ 9,200 psi. Velocity standard deviation was 12 fps, pressure standard deviation was 200 psi.

Test #3:

Sample size = 10

Same STS-type once-fired hull and the same load, but I substituted the Federal 209A primer for the Winchester 209. Average velocity was 1182 fps @ 9,200 psi. Velocity standard deviation was 26 fps. Pressure standard deviation was 600 psi. There was a larger extreme spread in both velocity and pressure: 69 fps and 2,000 psi. The highest pressure was 9,800 psi versus 9,600 psi in the same hull type using the Win 209. Still, I tentatively conclude that the 209A is interchangeable with the Win 209.

I didn't weigh each powder or shot charge but simply let the MEC Grabber do its thing. I used the MEC #34 bushing, which throws an average of 19 grs. Red Dot from my machine just as the specs say.

SAAMI maximum pressure for the 2-3/4" 12 gauge is 11,500 psi.

As I'm sure all of us know, chamber and bore variations will affect chamber pressures and velocities. I also strongly suspect that the once-fired hulls will have a tendency to reduce pressures WRT new hulls.