+3.5-5% Strength for 3.5s on Hit. Stacks 5 times.
+7.5-15% Weak Spot Damage. Weakspot Kills also ignore Enemy Hit Mass.
+10% Critical Chance for every 0.2-0.35 second while aiming. Stacks 10 times. Discharges all stacks upon firing.
+4.25-5% Strength for every Enemy you Stagger. Stacks 5 times.
Imagine the Bolter as the old Revolver - but with three times the clip size.
Core of the build are the Deadshot talent and the Surgical weapon blessing; this brings crit chance to 40% (+5% Veteran base, +5% Bolter base, +5% tree node, 25% Deadshot) plus whatever you get from Surgical (usually, at least +20-30%). Even the frowned upon Marksman's Focus keystone adds value for this one scaling reload speed and finesse damage (i.e. weakspot and crit damage).
Use Executioner's Stance to skip Bolter wield animation (if under pressure), to gain stun immunity, to counter Deadshot out of stamina effect, or to highlight targets in messy situations. Generally, adjust your playstyle, be mindful of your movement and positioning, protect your stamina at all costs, and convince yourself that every second spent with your melee weapon equipped means that you're failing the Emperor.
The only weakness of this build, besides player skill (it's quite the glass cannon), is arm shots.
Inform yourself about how Veteran's talents work: https://steamcommunity.com/sharedfiles/filedetails/?id=3094038976