Morris has supplied me with ten gauge shells for years. I am a reloader of Federal and Remington hulls because the RST shells are too pretty to shoot.

Back in the early 70's I worked with the DuPont ballistics lab developing buffered turkey loads utilizing Rem hulls. We were having trouble keeping the pressures where we wanted them. They suggested tying Federal hulls. The switch lowered the pressure by 1000 psi all else being equal.

gary what caused the pressure to go down...I would have guessed it to be the primer...charlie

Charlie, the components did not change. Just the hull. According to the ballisticians at the time, the difference was in the composition of the plastic used in the hulls. Federal plastic being more elastic.

I have been under the impression that hulls with composite base wads produced less pressure than an all plastic hull with all other factors being the same.

Tom Armbrust ran test on the effect on velocity from hulls which were new, once fired, up to about 10 reloading. Lowest velocity was the new hull. He theorized that the fired hulls were scuffed up from the firing, and created higher pressures/velocity from the reloads

I think this is the article about that test, loading various hulls up to 12 times. As far as I can see pressure and velocity stayed pretty consistent from new to loaded 12 times for most of them.

http://www.armbrust.acf2.org/caselife.htm

It's been a long time since I read the article. The Winchester tests describe what I was talking about

Hey, do you load your bismuth same as lead?