Once upon a time I distrusted bevel base bullets also. Not sure if I even remember why, or if it was just my innate trust in a perfectly square, sharp plain base. Logically it must be better than a bevel base.
Then I picked up a used Master Caster with several moulds, most of which were bevel base. I held my nose and decided that at the ridiculous close ranges that Cowboy Action Shooting took place at it simply didn't matter. The ease of the bullets dropping from the mould, the ease in starting the bullet into a case out weighed the potential accuracy gain offered by a flat base bullet at those short ranges.
One day I wanted to order a new Magma mould and I called to order a flat base mould and the owner asked me, "why?" I told him I wanted a more accurate bullet. He asked me if I ever tested a bevel base at more than cowboy distances. I had not, so I took my wife's Rossi .357 carbine and shot the Magma 38-130-RNFP with a bevel base at 80 yards. I then used a 125 grain flat base RNFP as a control. The bevel base out grouped the flat base. I know a very limited test, but it gave me food for thought. I no longer intrinsically distrust a bevel base.
Has anyone here ever shot a bevel base rifle bullet at any distance?