To further add on this:
Putting HS3 and CJ1 on the DMR-SD guarantees that you'll hit fully accurate shots while getting no extra bloom and a higher RoF, you essentially never have to worry about accuracy and get a lower TTK.
Also putting HB3 on it makes it a great LTL support weapon, and i'f your opponent happens to have CA3, chances are, you'll stun him i'f you time it right, this sabotages it's reverse dropoff a bit of course, but it'll still keep it's 3 shot potential to up to about 90m.
The DMR-SD is quite possibly one of the most flexible long range guns modding-wise and it's a criminally underrated/unknown fact, you should keep on trying stuff with it.