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 [Mag]). 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].