I built a room 12 x 24 inside a steel building 40 x 60 I want to anchor it to the floor with a remington nail gun how far apart do I shoot between every stud or every other I also didn't use pressure treated wood for bottom plate to concrete is that a problem (to late now)didn't think

I am in Electrical/Electronics, but until builder gets here, I have seen black Felt?paper between untreated and concrete, I would TapCon rather than Nail Gun. Spacing I can't help on. Good Luck.

Stratmando is right, Tapcons would be better than pins. However, sleeve anchors are your best bet. You should place them within one foot of each corner and on 36 inch centers from there. As far as not using treated plates, as long as they don't see a whole lot of moisture they should be all right for some time (10-15 years)

I would at least try to slip some felt under the bottom plate. The type of lumber we are seeing today I wouldn't give those plates 5 years. I pin all my interior walls. I use hilti but remington is good. Use a 2 1/2" pin with a washer and it will never move. Tap cons are also OK as well as sleeve anchors. Make sure if you do drill them you don't go all the way through the concrete or you could have bad moisture problems.
Mike