At most ranges here, you are not allowed to open carry with a holster unless LEO, MIL, etc. This goes for all ranges except for the "Action Pistol Range".
Concealed carry is permitted as long as it is...well...concealed.
To access the Action Pistol Range you are required to attend an 8 hour IPSC class and successfully compete in a single match without DQ'ing. The reasons why...insurance. Insident where a guy pulled the trigger as he was pulling from the holster. Bullet passed into his thigh, out above the knee, into the calf and out the foot. As a result, anyone wanting to be involved in any sport (or range) the involves drawing from a holster must complete a safety course. Free to members.
That said, you can shoot, but not compete or draw from a holster in the Action Pistol Range if you are supervised by an IPSC certiftied member.