RE shotguns -- CP is right about semi auto if serious about competition. Semi auto shotguns also help to reduce felt recoil over pumps or double barreled or single shots as well...
Shotguns are hard weapons to run reliably in most configurations... All take awhile to reload. With pumps, short stroking is common when folks are under stress. Semi-autos traditionally are less than reliable, especially if you want it to shoot an assortment of ammo, and double barrels and single shots really aren't ideal for serious use. And I say this despite a thing for double barreled sporting shotguns that I've purposely been denying simply b/c I can't justify on price + utility...
Semi autos do seem to be improving reliability though overall as the 3 gun market does seem to be pushing some innovation on reliability. Before you had just high end skeet competition guns tuned for reliability w/ a particular load, and then you had the field guns that required testing of every load to ensure function before hitting the field -- which most hunters don't do. They grab a box of whatever at their local ammo store on the way to the field...
Point being, all shotguns pose challenges -- the benefits of pumps vs semi-autos is that they're often things that can be correct through training (including dry firing and safe manipulation in the home) vs semi autos that often involve gunsmithing and specific ammo requirements, etc.
But to be clear, I don't consider myself a subject matter, including amateur, expert on any matter involving shotguns... So definitely listen to others here. Was just passing along some deals.
One thing I forgot to mention in earlier emails was that you'll often see sporter and home defense packages with shotguns -- so 2 barrels and one receiver. If looking to minimize cost and cover multiple shotgun basics, that might be something to consider.
And just fyi: On gas guns, there have been a lot of good deals lately on the Weatherby 459 semi-autos in both 12 and 20 gauge. I know nothing about them, but I'm opposed, on principle, to shotguns with stocks having pistol grips... Only without a stock do pistol grips make sense on shotguns in my personal opinion. I did look, and there don't appear to be any direct swaps for this particular model w/o diy modification of other options...
A search on slickguns will probably point you in the right direction if looking there. I want to say pricing around $400 for these if I recall correctly. Excepting my pistol grip exception, reviews on them are seemed pretty positive.
My interest was in 20 gauge semi-auto to see if the mrs preferred that to a 22lr gun for dealing with varmint issues when husband not home... .410 is too limiting IMO. I'm building her her own 10/22 instead, but haven't finalized optic yet.
