I don't see how the shoulder angle is going to refocus the direction of hot gases/powder. It still goes through the same neck, into the same throat, against the same bullet, for the same outcome.
The various powders you used can drastically change the test one way or the other. Stick powders are a LOT harder on barrel throats than ball powders. You mixed and match both and probably not the same between both tests. It is interesting though, but far from conclusive in any way. It is fun to mess around with such notions
Flinch
