You can sub a PCC for any division but you do not enjoy the scoring concessions for PCC if you're signed up for Factory or Practical. The same idea for the Heavy divisions.
7.0.1c Covers what you're talking about.
7.0.1 UNLIMITED, PRACTICAL & FACTORY DIVISIONS
Cartridge, Caliber & Gauge Requirements
a) Pistol: the minimum cartridge case dimensions are: 9x19mm, 9mm Luger, 9mm Parabellum, 9mm NATO or 9mm.
b) Rifle: .223 (5.56 x 45mm NATO) minimum rifle caliber.
c) FEATURED CLUB CONCESSION RIFLE: Pistol calibers are allowed. Minimum caliber is 5.7 x 28mm and maximum caliber is .45 ACP. Competitors must be registered in Pistol Caliber Divisions to be eligible for scoring concessions or be restricted to standard division scoring requirements.