I love Broadside. But It is a luxury card. Here I theorycraft a synergy deck.
Focus on killing Common to maximize the chance of proccing Broadside.
Bullet Penetration to maximize collateral headshots.
Weakspot damage to maximize the chance of killing on weakspot hit.
Collateral Broadside kills count as precision kills. This synergizes with Jim's Clean Kill trait and precision kill cards like Pep in Your Step and Sadistic. In The Zone if you want reload speed.
Start with enough damage to 1-shot headshot Common. Don't want enough damage to 1-shot bodyshot, because this is about precision kills.
Surplus Pouches is best final card for any build. Marked for Death is mandatory for me unless there's a better marker on the team.
Combat Knife + Broadside can clutch when surrounded.
Alternatives: Doomguy: no ADS. More move speed. Overwatch (scope). Ammo Stash.
https://www.twitch.tv/NiteCyper