Anapex, I'll put it up here for everyone to see (since I'm not badmouthing anyone else, I've bought from others and some were good experiences, so I'm not worried about any lawsuits or anything). My three favorite are:
-Clay's Hunting and Fishing (or something like that, Clay's I know for sure) in Ellicott City. Really friendly guy. He actually stopped me to talk while I was walking by his table at the last gunshow (I was going to leave him alone because I figured he was pretty busy). Only used handguns but usually some nice ones, good rifle selection from mil-surplus to new manufacture, ok prices, and really good to deal with (and I think the prices are negotiable). He is the one that is open Thurs and Fri evenings and Sat (most of the time anyway).
-Shooter's Discount in Arbutus. Small but usually nice selection of used handguns, usually large selection of used and mil-surplus rifles. Good prices and a great guy to deal with (my only problem as I've said before is I'll sometimes stop in, sometimes just to look for a moment, and I leave 2 hours later because of the great conversation- Clay's is almost as "bad" on this). He is the one that is Wen through Sat (he may also be open Sun but I'm not sure about that).
-The GunRack in Burtonsville. Good selection of new and used handguns and rifles (they've been carrying CZ for years). Prices vary from slightly better than average to slightly higher but the service is incredible. They are pretty much full-service (I think the owner is a gunsmith but I haven't had the need to find out for sure). They are also usually willing to talk for a while and they are certainly willing to help out a new shooter. The only drawback on this count is if a cop comes in they drop everyone else for the more important police customer and that tendency (even when dealing with me who had bought 4 guns from them in a year and a half and referred my best friend to them who bought a nearly $1k gun from them) has dropped them from my favorite to my third favorite. They are the one closed Sun and Mon (they aren't a one man operation though, there is one full-time employee in addition to the owner and there is sometimes a part-timer).
I live far enough away from Atlantic Arms in Rockville that they aren't on my list (I don't have enough experience with them) but I can say that everytime I go in there I get service that is right up there with the better small shops (and they aren't that small). The prices seem to be from slightly better than average to slightly higher. I don't know if they negotiate. If they were a little closer so I got there more often they'd probably be on my list too. I'm pretty sure they are 7 days a week, but most days (with a few exceptions) they close pretty early.