I've heard it's best for airsofters to come on certain weekends. Like the 2nd or 3rd weekend of the month or something along those lines. Is that still the case? Or is there a good sized open play airsoft crowd out every weekend?

Open play airsoft is the 1st and 3rd sundays of each month. Of you have facebook I would recommend finding the airsoft community page for the stl area

What Manta said. But if you have a huge amount of guys that want to play, call in advance and they might be able to work something out.

Open play airsoft is only available on the first and third Sunday of every month.