Pressure in a shotshell

[Big Friend Ten (BFT)]

Thanks John!

The above chart is measured in inches from the breach. I'd love to have one of those test barrels!

For all 4 powders the peak pressure is reached no more than 1 and 1/2 inches from the breach. That distance is not far from the top of the powder charge as measured from the base of the shell. Hmmm, maybe that's why the chambers of barrels have much thicker walls than do the rest of the barrels...

[J.B. Books]

Originally Posted by Mark Ouellette

Thanks John!

The above chart is measured in inches from the breach. I'd love to have one of those test barrels!

For all 4 powders the peak pressure is reached no more than 1 and 1/2 inches from the breach. That distance is not far from the top of the powder charge as measured from the base of the shell. Hmmm, maybe that's why the chambers of barrels have much thicker walls than do the rest of the barrels...

"That distance is not far from the top of the powder charge as measured from the base of the shell". Which coorelates to the shot charge starting to enter the forcing cone and meeting resistance. Longer more gradual forcing cones have long been recommended for reduced felt recoil, lower pressure, better patterns. Along with longer forcing cones there is overboring.

"Over-boring reduces friction between the wad and the barrel as the wad travels from the chamber through the bore and out the muzzle. This reduction in friction is generally thought to reduce felt recoil and deformation of the shot pellets which results in improved pattern integrity and an increase center-pattern density."

http://www.doncurrie.com/over-boring...-forcing-cones