Chamber pressures for 12 Gauge VH

[Bruce Day]

The origination date is unclear. P. 515, TPS. The table is based upon historical data from American manufacturers for gauges 10, 12, 16, 20, 28, 32, and 410. Although the table was published in a 1934 article, I have been unable to identify any differences between turn of the century guns and late 1920's guns that suggest that earlier guns were intended for less pressure. Parker shot guns met SAAMI pressures when SAAMI was established, and the pressures used by Parker and other noted makers became the foundation for SAAMI standards ( Small Arms and Ammunition Manufacturers Institute).

Assuming Mr. Cutler's VH 12 is a standard for the type, his gun was intended for a service load limit of between 9500 and 10,800 psi. Not knowing present condition of the barrels, I make no current recommendations. It would have been targeted with 1 1/8 of No. 7 shot at 3 dre if it is like most other 12ga 2 frame guns.

[J.B. Books]

Originally Posted by Bruce Day

I have been unable to identify any differences between turn of the century guns and late 1920's guns that suggest that earlier guns were intended for less pressure.

I have observed one difference in the earlier guns, thinner wrists. Most likely beefed up to handle greater recoil of heavier loads rather than greater pressure.

[Drew Hause]

Per Tom Armbrust:

3 Dr. Eq. 1 1/8 oz.
Winchester Trap Load
1,202 fps 9,600 psi

AA Xtra-Lite 1 oz WAAL12
1189 fps 8000 psi

AA 'Low noise Low recoil' 15/16 oz
980 fps 6,200 psi

[J.B. Books]

Originally Posted by Bruce Day

Assuming Mr. Cutler's VH 12 is a standard for the type, his gun was intended for a service load limit of between 9500 and 10,800 psi. Not knowing present condition of the barrels, I make no current recommendations.

Bruce according to the Parker Proof Load Table you reference, your numbers come from "Theoretical Service Pressure Pressure Limits...." on the left side. As you can see that would mean 2 3/4" 12ga guns were built to handle 125% greater pressure than 2 5/8" chambered guns. That looks like a little chink in the armor that 2 5/8 chambers were meant for 2 3/4 inch shells to me.