HD,

Sorry for the partial answer. Mr. Bell also tests paper hulls (Federal) loaded with one ounce of lead shot,
Clays powder, and a one piece plastic wad.

His results show a lower increase in pressure than the plastic hulls. 602 psi increase at the breech and also at the cone.
As he says, "not enough to worry about". The same test with the longer forcing cone reduces the pressure increase
to less than 100psi at one inch and 100psi at the cone.

JC

Last edited by JayCee; 08/22/13 12:17 PM.
"...it is always advisable to perceive clearly our ignorance."ť Charles Darwin