Remington Express combo, with both the short anti-social barrel, and a 28" with Rem-chokes.
Replace the 20" shorty with bead, for a 20" "Deer" barrel with rifle sights.
If someone wants to get the home defense version with the 2-shot extension magazine, I wouldn't quibble, but you lose the ability to easily use it for anything from two-legged predators to dove, quail, ducks, or clay pigeons.
If you add your own extension tube, get the clamp that anchors it to the barrel for additional stability. If you doink it out of place, you now have a pump action jam-a-matic. Personally, unless I'm expecting hordes of zombie walkers, 5 rounds is plenty to get the job done. If in doubt, don't grab the shotgun in the first place, grab a rifle that takes magazines.
Leave the wood stock right where it is. If, God forbid, you end up in court some day, it looks a mite less scary than ninja-black plastic with evil doodads.
Replace the foreend with something grippy; personal fave was the old Pachmayr Vindicator front end, because there's nothing close to better when your hands are wet or sweaty, but since Lyman bought Pachmayr out, the fucktard geniuses stopped making it, because smarter than our customers.
Pull out the craptastic plastic shell follower it has traditionally come with as factory-fresh, and replace it with any number of far better ones, ideally in a hi-viz color so you can tell at a glance that the tube is empty, and so it won't hang up in feeding or let the spring tangle up, unlike the tendency of the factory piece of crap.
If you're really motivated, replace the trigger guard safety with a larger one, and if you can get your hands on a metal trigger guard which they put on the law enforcement models (and used to put on
all 870 models before Remington went all apeshit with swapping in cheap-ass plastic parts) rock on with that. (You may want semi-pro or actual gunsmith assistance with making that last swap).
Swap the mag cap for one with a sling swivel mount, add a swivel base to the butt if it hasn't got it, and get a wide sling and a pair of QD swivels so you can add or remove a good carry sling as necessary.
I'm not a big fan of sidesaddle or buttstock shell holders, as if you need to use the thing around cover with your weak hand, they'll do a nice job of effing up your moviestar looks. Ghost ring sights are over-rated and over-priced, but either a fancy tritium front sight insert, or at minimum, 10 cents worth of glow-in-the-dark paint from the craft store on the front and rear sights are beyond value when you suddenly need to grab the thing at 0-dark-thirty because of a noise downstairs or outside.
I prefer a separate light rather than any of the pricey foreend lights, because they're invariably dead the minute you need them. Especially when a separate LED light can be had for only $5 at Horror Freight, and I usually lose them before I ever manage to kill a set of batteries.
That's about it.
I have one as a truck gun with a folding stock, but only because I can store it more compactly and unobtrusively in a locked tool bin. The only way to shoot them is
with the stock unfolded, not with just the pistol grip, especially if you use anything heavier than standard loads, unless you're a masochist.
Add something to carry extra ammo, whether a purpose-made 12 round or more pouch, a shell sling or bandoleer, or simply an old Alice canvas buttpack with a GP strap, and you've got a way to carry all the spare ammo you need for trap and skeet, sporting clays, or any serious riot, at all three of which mine set up exactly that way has been present for duty.
Your best friend for home add-ons is the
Brownell's 870-specific catalog, and if there's something you want that isn't there, you probably don't need it.
Ask a decent local gunsmith what parts they'd recommend for spares that you can replace, but at minimum, I'd have spares of the mag ratchet cap, mag spring, and shell follower, as they're cheap and easy to replace in about a minute yourself, but without any one of them, the gun is tits up except as a single shot.
That's what works for me.
But the true beauty of the weapon is that, like the AR-15 platform, it's a Lego weapon that has become so standard you can buy a metric fuckton of add-on or swap-out parts and make it into anything you want (as I'm sure the next 5 or 20 replies will amply demonstrate).
The only thing keeping the gun from being absolute perfection on earth is that they haven't moved the safety from the trigger guard to the top tang, where it belongs.
As long as the barrel is over 18" and it's >26" overall, the BATFE and the local constables don't get pissy.
