outside of auto-aim distances the BR will not hit the same spot after the 1st shot. the DMR will as it's essentially a magnum with a 6-shot body kill instead of a 7-shot body kill and a 2-shot + melee instead of a 3-shot + melee. other than that it's about range in terms of the differences between the two.
that's a long way of saying that the BR has significant recoil outside of auto-aim distances whereas the mag and DMR have little to none in comparison. crouched BR shots will greatly subdue recoil. however, as pointed out in the video below that is a good and a bad thing. the recoil in the BR is like a would-be aim forgiveness thing... you may miss but you'll still hit something. not so with the mag and DMR since the recoil is non-existent in comparison. these ladies fire straight and true.
this isn't my research. it's The CageyBee007
's check this out: https://www.youtube.com/watch?v=al7m8mP37gI