First, while a 12 gauge racking is a universal sound that produces autonomic release of body wastes in bg's, it is not the best choice for home defense. Second, that legally long barrel can easily be pulled/dislodged from your hands as you enter a room. Finally, the 00 buckshot most folks carry will produce potentially lethal collateral damage. A handgun held close in - with known ballistics - and with which you are well-versed and practiced in it's operation, is a far better choice. Your 3" 629 - and those 200gr Gold Dot CCI Blazer .44 Specials are a great solution.
Studying the Speer 200gr Gold Dot .44 Special (#4427) bullet's data sheet, one finds that it was designed for 800-1,000 fps - .44 Special to hot .44 Special levels (It's predecessor, #4425, was designed for higher velocity.). It reliably opens at 800 fps... to .72-.76", according to several tests. The newer .45 Colt 250gr Gold Dot (#4484) is rated at 800-1,200 fps - but I have not tested it at over900 fps. It reportedly also opens by 800+ fps.
In .44 Special, I have chrono-ed the Blazer 200gr GDHP, Georgia Arm's Starline brass version, and my own reloads, all with that Speer #4427 bullet. I get 805 fps from my 2.5" 296; 836 fps from my 3" 696; and 860 fps from my 4" 629MG - all plenty fast for proper operation. The 296 is my CCW and bedside HD firearm. I have a 2" 10 with Remington R38S12, 158gr +P LHPSWC's that makes 830+ fps from the snubby, on my wife's side. We also have a 5.5" .45 Colt Redhawk loaded with the Speer 250 gr GDHP's and 255gr LSWC's easily accessible as a backup. Everything launches from 800-850 fps, for my neighbors' sake... and should be sufficient for protection.
Now, which would I go out to the store and buy today for protection? Look around, both gun and ammo selection in DA .44 Special and .45 Colt is lacking even in a well stocked gun store. I'd get a ~2" .38/.357M snubby - an S&W 442/642 can double as a CCW - and load it with those 158gr LHPSWC's - or Speer's 135gr Gold Dots - both +P. Second would be a .45 ACP - with 230gr Gold Dot's or Hydra Shok's.
Of course, as a retired college instructor, I am often accused of suggesting others '...do as I say, not as I do!'. I keep both .44 Special & .45 Colt for home 'protection'... but I also reload, so I have lots of ammo!
A 'home protection' plan is important - assign a 'safe room' to retreat to - and have a cell phone to call for proper help - and a decent flashlight. When you call for help, tell them where you are and that you are armed. Have proper cover - and a clear shooting lane to your 'entry point'... and remember, Jack Bauer is a TV character...
Stainz