what is the datum diamater of the 6mm lapua br case and the datum diam of the 6mm br remington case.

[g n brezinski]

see above

 

[rsmithsr2]

me thinks you would have to ask the makers.
all else would be measurement of bought samples, which could vary.
( saami drawings are specs with datum points, but they do not make cases nor ammo, nor reamers)

 

[g n brezinski]

thank you

 

[FBecigneul]

You’ll not go wrong penciling in .470.
Lapua is .469 Remington is .470

 

[R.G. Robinett]

Along with the original Remington .308 URBR brass, there were/are numerous versions of the 6mm BR case: just above the extractor groove, via micrometer, all of the various cases manufactured by Remington, which I have had - 6MMBR; 7MMBR; Re. B.R. (small rifle primer .308), or, URBR - measured between 0.463" and 0.464" diameter. LENGTH can also be an issue - note the, "NOTICE . . ." on the accompanying pic - some serious confusion introduced there!!

The LAPUA and Norma manufactured brass usually measures 0.469+" just above the extractor-groove. The brass stamped R-P BR REM is the full .308 length, URBR stuff. Of course, the Remington made brass (DIAMETER) will fit into a LAPUA/NORMA chamber, but not vice-versa. Again, LENGTH may be a factor, and MUST be accounted for!!

I'd bet that the Rem. MARKETING brass couldn't accept having the 6BR NORMA moniker included on their box!! Oh, to accommodate experimenting, the no flash-hole brass was intentionally made. The 6BR was a case of poor marketing decisions . . . (puns intended)
Yes, confusion reigned, and continues . . . RG

 

[R.G. Robinett]

Here's a pic of the full length 308 Remington brass. RG