Hi Stuart,
I can't claim to know heaps about the 108's…I know the smallest group shot at 600 yards in the US was with these projectiles so I'd say they clearly work.
I tried them in my short necked BRX and found the bearing surface was to long for my chamber, meaning the lands pushed the projectile back passed the neck shoulder junction of the case….not good for accurate shooting.
My options were to have a gunsmith ream more free bore into the chamber or stay with the projectiles I was using,..I opted for the later.
Your standard BR has a much longer neck & so the problem I had might not occur in your rifle,..it depends on how your barrel chamber was cut.
About the only advice I can offer is to buy large numbers of the same batched projectile & order more well before you think you need them.
Sorry I can't be more help.
Regards,
Belly
Michael Bell