I have just brought a number 37 Shell holder to load some 338 Lapua Mag cases. On the bag it said for 416 Rigby nad 338 Lapua. I checked the stamped number its 37.
The once fired cases do not fit. Neither do the unfired cases.
Has anybody else had this problem?

You might try a #14. RCBS lists both. The #37 is for the Rigby cartridge. The #14 is for the Weatherby cartridge.

Thanks for the information.

You're welcome.