Mk III Helbore Sniper
 Veteran Build - Warhammer 40k: Darktide 

Down below is the list of all the breakpoints that I have tested for this build as well as detailed stats of my current Lasgun's roll.

Xray's abridgements:
[FCS = Fully Charged Shot, HCS = Half Charged Shot, RS = Regular (uncharged) shot]
[HS = Headshot, BS = Bodyshot (center mass hit, hitting enemy guns / hands / legs doesn't apply and has different breakpoints)]
[* = important]

Mk III Hellbore (75% damage, 80% Stopping Power; +20% Flak, +8% Specials; Surgical, Sustained Fire)
(I didn't include mutants in any of those tests as it's really tricky to hit their head, you're gonna be relying on crits / melee to deal with them. Bring a Chainsword.)

No Sniper Feat / Ultimate:
1 FCHS Trapper / Bomber / both Gunners / both Shotgunners *
1 FCBS Sniper *
1 HCBS All Shooter Types *
1 FCHS + 1 HCBS Flamer / Hound / A. Rager
3 FCBS Mauler / Bulwark
2 FCHS Bulwark
4 FCHS + 1 HCBS Crusher
3 FCBS + 1 HCBS Hound
2 FCBS Flak Rager
2 FCBS + 1 HCBS Maniac Rager
2 FCHS + 1 HCBS Reaper
1 FCBS + 1 RS both Shotgunners

With Ultimate (the Bigger they Are), no Sniper feat:
Almost 1 FCHS Reaper (1 RS needed to finish)
Almost 2 FCHS Crusher (2 RS / 1 HCBS needed to finish)
1 FCHS Bulwark / Flamer / Hound / both Ragers *
1 FCBS Trapper / Bomber *
2 FCS Mauler (anywhere) *
2 FCBS both Gunners / both Shotgunners

With Sniper feat, no Ultimate: 
2 FCHS Reaper (20 m; 3 health left at 19 m) *
1 FCHS Flamer (20 m; 1 health left at 19 m) *
1 FCBS Trapper (19 m) *
1 FCBS Bomber (18 m) *
1 FCBS both Shotgunners (16 m) *
2 FCBS both Gunners (15 m)
4 FCHS Crusher (20 m)

With Sniper and Ultimate (the Bigger they Are):
1 FCHS Reaper (16 m; 14 health left at 15 m) *
2 FCHS Crusher (15 m) *
1 FCBS + 1 HCBS Mauler (25 m)
1 FCBS Flamer (26 m)