This weapon's not that bad. People are very mean to it. It's a bit disappointing for how lategame you get it, but it's a semi-auto pistol that can put six bullets in the air in a second with base 27% crit chance each.

I also think building this for headshots are silly. Yes, that's how you can squeeze the most damage out of it, but with its base fire rate, recoil and accuracy, you might have a hard time keeping [Galvanized Crosshairs] and Secondary Deadhead active. Instead, I believe the status chance mods and [Creeping Bullseye] play more to the Mars' strengths. It is well worth sacrificing 20% fire rate for a base 80% crit chance, especially when anyone without a macro will struggle to consistently hit 6 trigger pulls a second.

Building this weapon purely for the alt fire is also kinda dumb. If you're trying to turn this into a status-lobbing AOE machine, you should probably just pick a different weapon. The alt fire is a good backup option to have, but as many have observed, its base radius is pretty poor. I choose to build for primary fire, but keep that alt fire in your back pocket, because a built-in grenade is pretty nifty. However, the existence of the alt fire DOES prevent the usage of [Semi-Pistol Cannonade], tragically.

[Galvanized Shot] and [Galvanized Diffusion] are pretty much necessities on any pistol, but I think this weapon in particular does make for a nice 'gundition overload' build with its decent status chance and high fire rate. I lent into this with Secondary Encumber to occasionally smack an extra free status on. At base, half your shots apply a status (40% of the time it'll be Heat, 30% will be Viral and occasionally you'll get a physical), and that status has a 1/4 chance to also pop a totally random extra status on for up to 120% bonus direct damage to a target. Mash that trigger and watch the numbers get bigger, headshots or no.
Cascadia Flare is another potent Arcane option: as long as you keep landing shots and inflicting Heat stacks, you'll build up an absurd damage increase (additive to [Hornet Strike]).

If you can't get your hands on the Primed mods, substitute in the regular versions; they'll probably get the job done. [Creeping Bullseye] is flexible for [Primed Pistol Gambit] but I do really believe that Bullseye is better here.