Posted by Tom Martin on November 27, 2014, 4:48 pm, in reply to "20 in 12 Pressure"
Sine the peak pressure in a shotgun develops before the charge leaves the chamber, and the insert is as long as the chamber, there would be no reduction in pressure. Measuring the pressure would be difficult because a trai gauge over the chamber won't work, and either a crusher gauge or a piezo gauge would have to inserted through the side of the insert as well as the test barrel. In ay case there will be an abrupt drop in pressure as soon as the charge leaves the insert, as there is a finite amount of pressure which now has to occupy a larger space.