You guys are way over-thinking this.
1) Buy 10/22. Get the SS one, the barrel will look good hanging over you front door when you:
2) Replace it with a 12" fluted jobbie - you will need the kwick handling and the extra cooling.
3) Get a composite tac-style stock. MUST-HAVE, so that :
4) you need two (minimum!) optics, including a SWAT-style scope, and a red laser, a green laser, a couple flashlights, and a bipod mount. Better if you sling a paintball grenade launcher under it, too - so you can mark 'em up for later if you miss with the first mag.
5) make sure your scope is a sniper one, because you did mention the 100km kill-shot that may be required.
6) ONLY use sub-sonic rounds. Like you said, the mom may be around somewhere.
7) the dual-50 round setup looks mad tite - I gotta get me some of that action.
Remember: practice, practice, practice. You've got the sub-sonics, so you can do it in your backyard. Or you front yard. Squirrels, mice, girl scouts (I'll take ALL you cookies, you little BAM BAM BAM), the neighbour's dog, whut evs.