I use one 8-rd caddy as my primary shell carrier (AP 4x4), and then have extra 4-rd and 6-rd carriers (California Comp) that I'll clip on if the stage is shotgun-heavy. I also use an elasticized buttstock shell carrier on my forearm if the stage design makes it a good idea (e.g. carry slugs on it for single loading).
HSGI double taco rifle mag pouch as primary for rifle, and a teklok Bladetech single mag pouch that I'll add if the stage calls for it.
Red Tip Bullet had AP Custom 4x4 carriers, but they seem to be gone now. I'd email Nick to see if they're still available, he had the best prices on that item by far. Everything can be had at Brownells, though your local shop might be able to help. One Shot Tactical (site sponsor) had a good selection, as well as DS Tactical, too.