Gunny,and bronze armor?

Is it useful,or useless?

Depends on what your using your gunner for and what your other endorsements are.

Killin' and chillin' , Gold : ACC , Silver : RoF , Bronze : armor?

I'd switch Armour and ROF. If you put on your Numbers Game hat, the difference between Silver and Bronze Armour is greater than the difference between Silver and Bronze ROF.

Also worth mentioning:

No armor @ 700 HP requires 5 sniper rifle bodyshots to drop you.
Bronze armor @ 800 HP still requires 5 bodyshots.
Silver armor @ 900 HP requires 6 bodyshots.
Gold armor @ 1000 HP is still 6 bodyshots.

Against Snipers, your mortal enemy as a Gunner, silver armor is where the money's at. Of course, against good Snipers that can land headshots even as you dodge, you're still in for a world of hurt.

I always run Gold armor. I'm big and slow, therefore everyone will shoot at me, not only Snipers. Survivability is the key! No death = more pros/bots streaks = more money = more Juice = more Turrets raped = win.