I tried shooting walls and grounds by stationary ADS at distance with some combination of attachments to check its effect
But I feel match barrel of DSG has no expected effects: Shot impact point by DSG with match barrel seems like too inaccurate　When shot minimum time　interval.
On the contrary, equipping no attachments seems better than match barrel.

'Course Match Barrel won't do anything, DSG's accuracy is already maxed out. You'll want to use Muzzle Brake for the reduced recoil.

I can't use the dsg yet :/