Wait, there is a Harrisburg gun show this weekend?
At the Farm Show Complex. The web site states 1000 tables and free parking, lots of opportunity for higher-capacity mags, carrying out C & R guns, ammo, selection, carrying a weapon while in PA., ..........but I'm sure the Timonium show will be fine too.
Then next weekend is the Oaks show, with 2000 advertised tables and free parking that, for the most part, will be an adventure in itself,