I'm shooting my first local 3 gun match and one of the divisions is 2x4. Which under the UML rule book explains as a Rifle, PCR (PCC I guess?), Pistol, and Shotgun. with no limitations.  So my question is how does that work? Are you required to used all applicable firearms on a stage? Or do you get to pick and choose based on the stage design?  I've shot a few 3 gun matches out of state and 2x4 wasn't a thing when I registered.  I did a google search and there isn't a ton of info on it.

The latter. Bring all 4 guns, shoot two on each stage. Read the stage briefing for details.