My wife sewed me a bandoleer out of military surplus suspenders. It holds fifteen shells where my support hand can reach them quickly AND holds my pants up! She also left a provision at the bottom for me to clip my 10 shot slug pouch on it.
I know that it is not ultimately tacti-cool but it works well for 3 gun.
For long shotgun stages I have run with my bandoleer, slug pouch, butt cuff, and I actually have another butt cuff that I wear on my forearm. (Don't knock it until you try it, it makes for a surprisingly fast reload, but you need big forearms).
The most common gear used in 3 gunning for shotgun shells are from www.3gungear.com They are hard core competitors who make great stuff. You will also see a lot of belt shell caddys. I have never used one of these so I can't tell you where the best place to get them is.
I'm looking for something to use mostly for 3 gun or "combat" shotgun comp. I wanted a vest because after messing with older alice gear it works o.k. but that vest I saw was great. It carried
12 rnds of 12ga so you removed them from the left or the right and also had pistol mag pouches so you have one piece of gear for the 2 guns( and it was $75).
P.S. I know better than buying a bunch of "tactical" nonsense
because I figured out
A. I'm not a SWAT cop and I don't want to be(and I'm glad others do)
B. I'm not a green beret/navy seal/force recon guy and I don't want to play one on the weekend.
C. after reading about SF exp in veitnam I know that one guy in the middle of a bad situation is in deep doo-doo no matter what kind of gear he has.
I found the solution right under my nose! 2 3/4" 12 ga shells fit in my 1923 us cartrige belt! If I put one shell against the bottom then I can put 3 standing up-right and it works very slickly!!