Bevel bases are not an asset when using RCBS or Lyman sizers but in fact make the sizing process a mess. I recommend them only if the customer is using a Star, which cannot square them up as the above two sizers can. Not all shooters agree that bevel base help accuracy when using a Star sizer, and I don't argue with them on it, because it isn't a big deal either way.
When using an RCBS or Lyman sizer, I reccomend cupping the stop plug out a bit and facing a dead square ring on the outside edge, about 1/32 inch wide. imprint this lightly into the base of all bullets, whether gc or pb, and you'll see an accuracy improvement. Especially on large caliber light weight bullets, which tend to roll easier than long slim ones, when they leave the muzzle, if the base is out of square. Especially if the crown is out of square also, as this condition is sometimes canceled by out of square bases with some shots and doubled with others. If the bullet bases are all dead square and don't get knocked out of square during shooting, an out of square crown is not a detriment to accuracy. Doesn't matter, jacketed or cast.
