greetings michael,
first of all let me say, 'i have over 200 molds'. many, many of them are custom molds. and no one, i say no one makes a better mold than dave mos.
try this num. 479 394 5895. he works as a machchinest mgr for the texzs oil co's. and is off on fri, sat and sun..
now, is that 2.5 degrees on one side or both??? and... what is the depth of the chamber where the case ends?? example; if the case is .015 thick at the rim, how deep is the chamber in the bore?? where the case mouth ends, is there a smooth transition into the bore with no step down??..
in breech seating it shouldn't make much of a diff. but, here we are starting to talk about that last 2-3 percent accuracy. repeatability becomes very important. icluding how the fouling builds up in that small area between the case and the bore.
to think i gave up benchrest shooting years ago cause chasing that last 1 or 2 thousands on an inch was too much trouble and time consuming..

..ttfn..grampa..