Posted by Drew Hause on December 23, 2013, 2:46 pm, in reply to "Re: Chamber inserts"
Just to clarify, Sherman Bell's report to Gauge-Mate back in 2006
In the 12-gauge gun with 20-gauge adapters: A Winchester 20g AA Sporting Clays factory load of 7/8 ounces of #7 1/2 lead shot, fired in a Silver adapter, gave a velocity of 1319 ft/second and pressure of 7700 psi. The same 20-gauge load fired in a Go1d adapter gave a velocity of 1324 ft/second and developed a pressure of 7800 psi.
Bell did not report the psi of the factory 20g AA load, but it is very likely greater than 10,000.