If you live in congested area, where penetration thru walls
COULD be a problem, use a turkey load in a shotgun. #4 shot loads are available in 20 ga., and unless the target is wearing protection, they will
not be able to function in any capacity after a direct hit! Slugs and buck
WILL over penetrate in a HD role, especially in an apartment complex.
Better safe than sorry. I can see how #8-#9 promo 20 ga. dove loads from Wally world could give insufficient penetration/stopping power if the target was wearing several layers of clothes under a heavy coat (Chicago in February!) but that's the only way. In a warmer climate, that shouldn't be an issue.
If you live in the country, alone, you'll be fine. Hell, use a .50 BMG for HD, if you want!
Not so sure I'd want a bolt action .22 in that role....
The 10/22 is a great gun! My wife gave me mine for a Christmas present just after we got married 20 yrs ago. As far as accuracy goes, unless you're 1 of those people who expect 1/4" groups out of a new $200 gun right out of the box, buy 1! Mine is very accurate having fed me
many head shot squirrels, not to mention winning several informal shooting competitions over the years.
Other than a scope, it's completely stock. As mentioned, is it very 'customizable' if so desired, down the road.
As several have posted, the 10/22 and a 20 ga. pump are just about pefect choices for 1st guns. And you can buy both on your budget, as well as ammo to get good wih them.
Watch the forums here, check on gunbroker.com (tho they're usually a little high), pawn shops, and watch your local newspaper. Some of the best deals can be found on a radio station's 'swap shops', at least in a rural area.
Remember, in a HD situation, 1 of the most important things is to
have a gun - be familiar with it, and of the mind set to use it. Many criminals (sober? 1s anyway!) are cowards, and are after 'easy' money, and the sight of an armed, determined person,
may be enough to help convince him/her to change their course of action!
Good luck, and practice!