Room Brooms....
I'm not much of a shotty fan.
I would get a NIB left hand 870 12ga or maybe a Ithaca Defender 18" barrel with extended magazine.
Browning had a cool BPS 12ga all-weather(a tough grey-nickel) with a extended mag tube but it was cut about 3 years ago.
In general, the Remington 887 Tactical 12ga is a great value for a home defense or duty weapon. It's safe, robust, easy to service/clean & looks like a ticked off Pit Bull,
.
The Mossberg 590 milspec & the 870 lend themselves to after market stuff.
There are many US firms & gunsmiths that do custom jobs.
Wilson Combat is considered a top source for LE grade features.
Magpul's new "furniture"(a UK military term) for the 12ga 870 & 500 series are impressive.
For one hand use or "wounded" methods, Id suggest a pistol grip style(with stock). Massad Ayoob;
www.massadayoobgroup.com wrote a gun press item about these shotguns. Ayoob also wrote a
Stressfire tactics book for pump/semi auto shotguns.
Surefire markets a bright fore-end light for the 870 series but I prefer the lesser known EOTech version(includes a strobe).
The Warhammer add-on is a smart choice too. It acts as a heat shield & you can use the 1913 rails to add kit(lasers, scopes, lights, etc).
Nordic Components(NC) is well known for custom shotgun features & defense products. I like the magazine extensions but there are other well engineered brands.
Finally, do
not use the Knoxx Spec Ops 12ga stock from
www.blackhawk.com . They no longer sell these shotgun parts & the tactical stock versions are reportedly unsafe. Blackhawk themselves post a safety warning.
CF
See;
www.brownells.com www.midwayusa.com www.surefire.com www.natchezss.com www.galls.com www.cabelas.com www.grafs.com www.policehq.com www.deltaforce.com www.magpul.com www.gunzilla.us www.deltapress.com www.gunvideo.com www.nra.org