Pretty wet, here on the coast, even when it's supposedly dry.
I have different types of barrels on various semi-auto (Militia!!!) firearms. I see stainless steel and chrome-moly barrels get more gunky than chrome-lined, either after shooting or just over time.
I've had good luck taking a 20 gauge bore mop and some gun-metal polish (I use Hoppes Gunmetal Polish in a squeeze tube). I put a cleaning rod in a drill motor, insert the bore mop and paste into the chamber and give it about 10 seconds of spin city time.
A sqiurt or two of brake cleaner and the chamber is sparkly clean and smoooooooooooth.
Anyway, it has helped some of those sticky chambers, quite a bit.
I have been using Universal Gun Grease on the firearms, as well. I apply a very light coat to the surfaces of the firearm, except the barrel and chamber, and really work it into the pores with my fingers or a brush. Works on paint, as well.
I rub the firearm down with a cloth to remove any built up grease, since I don't want the thing to burst into flames while I'm holding it.