Most matches have magnified and non magnified divisions (irons would be non magnified), as well as open and heavy metal.
Breakdown usually goes kinda like this:
Magnified/Tactical/Tac Optics:
Pistol iron sights only, must meet USPSA Limited division criteria
Shotgun iron sights only, tube fed, loaded by hand, 8+1 capacity
Rifle single magnified optic
Non magnified/Limited/Tac Irons:
Same pistol and shotgun rules
Rifle must have non magnified sighting system (irons, red dot, or non magnifying scope)
Open:
Pistol can meet USPSA open division criteria
Shotgun can be mag fed, optic equipped, loaded however you want
Rifle can have a bipod, and as many optical or electronic sights as you want
Heavy metal:
Pistol must be a 45 and has a capacity limit of 8 or 10 depending on the match (may also be 1911 only)
Shotgun must be a pump action with 8+1 capacity
Rifle must be a 308, non magnified sighting system, and a 20 round capacity limit
Read the rules for whatever match you go to, they will all be different and none of them use the USPSA multigun rulebook. That rulebook is only used at USPSA sanctioned matches.
