Don't quite understand what caliber you mean-
the 338 Lapua is a 416 Rigby necked down to 338 and the case shortened a bit.
Need a little more specifics before anybody can help....
My son has a .338 Lapua loaded cartridge that he just had a rifle made up for but I HAVE A CARTRIDGE here that is slightly longer and stamped .416 and its necked down to .338! Matter of fact it's got a 300 gr. Sierra HPMK stuck in the front! Use to be an ole boy on here from Pa. name of Daryl Cassell I believe! He sent me the cartridge and I can't locate him! I'm thinking about making one up....but....????? can't locate him!!
groundpounder
If you are talking about a 416 Rigby case necked down to a 338, I have been shooting one since 1996. I have taken elk and moose with it and love it - building a new rifle for this cartridge.