Like the title says, What is the difference between the 6mm BR Remington and 6mm BR Norma?
Is there anything that would make one more accurate than the other?
My intended use will be 600 & 1000 yard F-class target shooting.

Presently I have barrels in 22-250 AI with 1-8 twist and 260 Remington with 1-8 twist. The 260 was intended to be usable with any of the various 139-142 grain target bullets but presently it shoots them badly. It is a tack driver out to 600 with the 120's at 3200 fps but on paper that load is iffy at 1000 yards.
At this point my debate is if I should try another barrel in 6.5mm or try a 6mm caliber.

There are some slight differences in case dimensions but I think the consensus is the Lapua brass is by far the best and a lot less expensive than Norma.....most benchrest 'smiths have the Lapua 6BR reamer.....if I were serious about long range shooting I would probably have it chambered for the "Dasher" version which has the shoulder pushed forward for more capacity. I would talk to Dan Dowling who was one of the originators of the Dasher.

The main difference between the two is the length of the throat. The 6mm BR Rem is throated to chamber bullets up to about 70 gr, maybe as much as 80. The throat for the 6BR Norma is much longer and can accept the very long bullet over 100gr allowing for more powder since the bullet is not seated as deep. I have recently purchased both Remington and Lapua brass and took several measurements on both. There were only minor differences between them. The Lapua brass was about .002 larger in diameter at the web and there was about .003 difference in overall case length. Some of the older Rem brass and early chambers are much shorter, so be careful if you have a 6BR Rem barrel of unknown origin.

There have been changes in the dimensions of the Remington cartridge since it's inception. It is longer (1.570 as opposed to 1.520) and the neck is larger (.271 from .266). The earlier measurments on the Remington are from info I got in 1980. So that by the latest info I have the two are essentially identical. For a rifle for "F" class I would chamber to use Lapua brass and cut the throat to an overall depth of .2 past the end of the chamber. This seems to work well for the 107 Sierras. Regards, Bill.