OK, thanks for the reference Ted.
The link won't work, but it's simple to find with a search.
I believe you misinterpret that section.
In building their proof loads, The Masters are directed to apply at least 30% overload both in the chamber and at 162mm.
This does not necessarily require two cartridges.
Here's the key point. When measuring 'service' pressure at 162mm, the value will be someplace between 2.000 and 4,000 psi depending on which chart you run across and from which era. The intent of the proof rule is to apply 30% more of THAT measured pressure, not 30% more than PEAK pressure at that point.
They are not testing the 162mm point with chamber pressure.
It is possible that to achieve this, two cartridges are used. The reason for it would be to reduce peak chamber pressure while still applying sufficient PSI at the 162mm point.
I did find one black powder proof curve that showed near 2 tons of pressure at approximately the 9" point, so this appears to be nothing new.
Last edited by Shotgunjones; 08/01/17 03:50 PM. Reason: chart values
