12.7mm vs. 9.5mm ammunition really. Sure the BR’s bullet has more powder behind it but its probably a lighter load overall. Recoil control if I had to guess.
I mean technically the DMR and AR should hit the same because they’re firing exactly the same round (7.62x51mm armor peircing FMJ) but they dont.
(Also, hilariously, its RRR used to be better Im pretty sure. They jsut went through nerfing it for the finals. LUL)