It would be called "Gun God".
Now before any of you start thinking the wrong thing, its not a CoD clone.
Its a Tycoon type game, where you sell, make, buy, and re-sell weaponry and ammo.
You can trade guns for better ones, and sell those and market price to customers, to produce cheap disposable guns for low cost, and out produce your competition.
The better quality guns to supply, and the farther ahead of schedule you provide them, the more "good" renown you get. The worse the quality, and the seedier people you sell them to, the more "bad" renown you get.
Selling guns to homeowners, cops, and gun enthusiasts wont always get you the most money, but its steady business thats very safe.
Selling guns to thiefs, felons and people who want the guns "off the books", will get you alot of extra cash. But it can cause the police to try and shut you down, as well as increase the chance of you getting robbed yourself. (Your giving them the weapons to rob you. Dont expect it to be safe)
You can create, upgrade, and pimp guns in your workshop. While the client might want a Standard black M4, giving him an adjustable stock and a free box of ammo might get you a massive tip. Where as painting it gold and giving it a sniper scope could anger him, and lose you income, and potentially customers. The type of upgrades the client wants will be dictated by what kind of client he is.