FNG wondering about preferred barrel length, gauge, and action for 3-gun? Have an 18.5" pump and several 26"-28" semi waterfowlers from .410-12gauge. GTG, trick one out, or buy 22" Mossy 930 JW?
If you are starting out then use any of the 12 gauges that you have. The 26" would be a good place to start. Get a extended mag tube and let the big dog eat. If your buying I would go with a 21 or 24" in 12 gauge.