This was originally a meme build, but since this thing hits like a freight train I've optimized it more for actual use.

• Exilus mod is up to preference, though you should be wary of the default polarity if you don't want to use a forma for it. [Hush] in particular is useful for stealth missions and is probably a better pick than any other Exilus mod in this case. Primary Deadhead passively halves recoil, but in absence of that or if you want even less recoil Stabilizer could also be a good pick.
• If you have a good critical or damage Riven I would recommend swapping [Bladed Rounds] or [Critical Delay] for it. You'll need an extra forma to fit it, but the increase in damage will (probably) be worth it. For reference, my riven with +heat, +crit chance, +crit dmg, and -status chance makes this deal around 50% more damage overall per hit when taking the place of Bladed Rounds.
• For fighting anything that can survive more than one hit from this, swap Bladed Rounds or Critical Delay for Galvanized Aptitude.
• You can swap Primary Deadhead for Primary Merciless, but you'd be trading much faster stacks, far longer stack duration, increased headshot damage multiplier, and halved recoil for not having to hit headshots to stack (which is kind of pointless since you should be hitting headshots anyways) and a small reload speed increase. In other words, use Deadhead.