I'd look at getting a push through sizer i.e. lee style in .367" and running the bullets trhough there to see if that helps. The thing with lyman sizers is they don't always size the nose of the bullet sufficiently.
Exactly. You don't want to size more than needed. Find the tightest diameter that will chamber. That's the benefit of an LBT bullet. It fills the throat.
Select a powder that takes up at least 50% of case volume. You can use dacron in between. Having a lube groove exposed in the above fashion, even two, won't really have an effect. You'll be beating the boys who fool with their fast burning pistol powders and are very careful to make sure that a lube groove is not exposed. Yeah, they need to worry about it. They also need to worry about a double charge.
