Revolver, Autoloader or Conversion: Three Kinds of .45 That Don’t Interchange
Bore diameter tells you almost nothing about whether a cartridge will work in a given gun. The base of the case does: a rim for a revolver cylinder, no rim for a magazine, and in a few cases a deliberately awkward length that keeps a hot round out of the wrong chamber.
Sorting this set by that one feature takes a minute and prevents most of the expensive errors.
Rimmed, for a revolver cylinder...