For stuff like 3-gun and perhaps tactical training, whats the most efficient and suggested way(s) of storing extra shells and getting at them with minimal hassle when using a pump action? I've never gone 3-gunning or taken a shotgun course but I'd like to absorb as much as I can before I spend money on a class (one day hopefully) so I can utilize the limited class time I have on honing techniques rather than starting off from square one and overloading my brain. I haven't really given it any thought thusfar as I own a Saiga-12 with 10rnd mags, but I got an 870 (build in process) not too long ago.

On-gun shell solutions seem somewhat bulky, limited in quantity, and might change the balance of the shotgun. I considered the 4-6 shell Mesa shell holders before on the non-chamber side. Anything chamber-side mounted would appear to be awkward if you wanted to load shells into an open chamber directly with your strong hand.

The molle/vest/lbe-setups look nice if the holders are relatively open and unhindered as far as reaching down for them. They're kind of out of your field of vision so you'd have to use them extensively to get used to it or take a peek down I would think unless you have great tactile memory. There are several different brands out there. Most look like pouches with elastic bands and a flap. I don't know how well the flaps fold back (or if they stay back) for easy access during shooting.

I considered the forearm mounted solution and it looks good on paper but I don't know if it works well in real life. I had a thought experiment on using one unit on either forearm as it keeps shells nearby and within peripheral vision. A supporting arm shellholder would work with the strong hand plucking shells and dumping directly into an open chamber for single shots whilst keeping the weapon trained on the target using the supporting hand to hold up the weapon.

Strong arm shellholder would use the supporting hand plucking shells to fill up the tube mag while the strong arm holds on the grip and keeps the shotgun tucked tight against the shoulder and trained on the target (might be harder if the shotgun is front heavy). Of course, this only gives you 16 total rounds (8 per arm) compared to probably much more on a vest, but more than the shotgun-mounted solution.

If anyone can chime in with some suggestions, products, experience, etc., let me know. Let me know if I am an absolute moron and steer me down the right path