Larry Gibson· Registered
With that load bullet jump is not the issue. Over sizing the case for the chamber is, along with using regular dies.I seem to find conflicting opinions re bullet jump and pressure. Some say touching the lands can cause 80,000 psi, some say too much jump will raise pressure 7,000. Other say different bullets need different jumps. Or seating a bullet an extra .030 into the case causes pressure to rise.
41.5 gr IMR 4895 168s is giving me flat primers and short case life, lots of stretching. Jump is about my last variable.
Suggest you get the regualr (SB die is not needed) RCBS X-Die to FL size your cases. I get 20+ firing per case with LC brass and stretching is contained so I do not trim at all.
With either the X-Die or the FL die you are using back the die out one full turn. Size a fired case and attempt to chmaber it not letting the bolt slam shut but just snaping over the rim. It should not chamber as the case headspace dimension should be too long. Turn the die in 1/8th turn and size/chamber again. Repeat until the case with just chamber. The cases then are being sized so their headspace "fits" the chmaber headspace on your rifle. Lock the die in that position.
The X-Die is the real and easiest solution.