Originally Posted by ronlaughlin

This morning i fired a few loads in the Triumph using W209 primer. The W209 grew about 0.010". The STS primer has plenty of fire for BH, but i am inclined to think the wouldn't be the best to use in my Triumph, because of their length. They would grow much more than the W209, and blow by would probably be an issue. If all Triumph have similar headspace, the W209 is probably the primer that will fit the best.

I believe my next breech plug project will be to decrease the headspace of the Triumph, so that STS will be the primer of choice in my rifle. Currently i am doing the same thing for one of my Omega.