Primary Plated Round since it has a higher maximum damage bonus than all of the other primary arcanes with [Tenora]'s magazine size (same bonus as maxed SP arcanes if you reload with ~80 rounds left in the magazine). Primary Dexterity is a good alternative choice if you don't have plated round but do have a good slash melee, or Primary Merciless if you don't.

If you don't like banes, swap it out for Serration.

If the reload speed is too low for your tastes, swap out galv scope for [Primed Fast Hands] and use something like Smoke Shadow to get back to orange crits