Any good early game (Act2) Mercenary build? Aside from grenadier

I'm playing co-op as a mercenary and my damage isn't that high in act 2. I tried solo and it was way better but I want to play Co-op with my friends but we literally need alot of time to kill bosses. We really struggle but I feel like the reason is my build. I tried using grenadier and I didn't really enjoy it. I got the mask that ignites enemies too. I'm currently using high velocity shots with scatter and double barrel coupled with flash grenades against 1 targets and galavic shards or something like that with pierce and lightning infusion along with herald of thunder for groups of enemies. I tried looking up some builds but most of them are endgame or near endgame. I currently only have access to skill gems level 7 and support gems level 1.