Originally Posted By: chevrofreak
.410 is quite underpowered. It's less powerful than most of the larger handgun cartridges, even when using slugs. The benefit is the lessened recoil would make it easier for a small female to use.
Your 500 would be fine, but you will want to reconsider a pistol grip. Pistol grip 12ga guns aren't that fun to shoot, and you lose a lot of control of the weapon. Get yourself a SpeedFeed or Knox butt stock with built in pistol grip. It will make it more manageable, and some of them have built in recoil reducing features.
Do not use birdshot for home defense. Period. Sure it may stay one tight cloud of lead until it hits the person, but it will disperse and slow very quickly when it hits them. You probably won't get the penetration needed to do the necessary damage.
Some people modify birdshot loads by cutting a ring around the hull below the wad. This makes the front of the hull tear away and stay in one solid piece until it hits the target. This can do a lot of damage to the target, but many guns will not eject the stubby case that's left behind. I've shot bottles of water with these and the destruction is impressive.
Video of said bottle. You can see the forward section of hull, and the wad land just above the CD spindles shortly after the explosion. I wouldn't recommend using this type of load in a barrel that has a choke. If you can fit a dime in the muzzle of your 12ga then it should be safe.
Get some low recoil tactical buckshot and you'll be good to go.
Check out the articles on the .410 and how some of the loads will actually surpass the penetration/damage of a .357 magnum. Recoil is manageable for females/smaller folks, etc. I would not lose any sleep at all if all i had in a HD scenario was a Mossberg HS410. The HS410 is a solid weapon.