Some notes on case neck expanders;
There were a number of difference M-type die expanders used for the Lyman 310 system. Many of them are much better for cast bullets than the current Lyman production. Ex: 38/357 available in .357 and .358. 45 hangun in .452 and .454. Various 30 caliber sizes from .308 to .313.
I have a new set of RCBS expanders from .308 to .311. Two measure dead nuts on, and two are .0002 undersize (not enough to matter)