About the nails.... fella was right to say 'check with your building inspector', for sure. Here in MI there are specific 'pole barn nails' that IIRC may not be coated/plated other than 'bright' as with common nuts/bolts. YMMV, but these 'ring-shank'-types are required for all supporting structures, headers, etc. We also use a special fat 1 1/4" galvanized for j-hangers, storm ties and the like. Some have a '10' on the head for easy ID when inspected. Never easy on lumber if nails need R&R'd to pass code, so be sure to take notes whenever criteria are spelled out.
In the framer-gun, and for light or non-load-bearing work I often use (Stanley-Bos) 12d vs 16d, tho' both are indeed thinner that 'commons' for the rosin coating that enhances hold (often called 'sinkers', btw). The 12d's are 3" vs 3 1/4" long. Since 1/4" doesn't leave much out there to clinch, sometimes it's as well just to eliminate the points protruding, but an extra nail may be indicated here & there. What's nice too is that when toe-nailing studs there may be less splitting when jamming several in. Oh, and the lighter gauge makes slightly smaller holes if a careless helper runs one through your finger. BTDT and came out lucky ...