Scoring is based on the outermost ring, rather than the innermost ring?

Huh. I'd have expected it to be based on the center, but I guess the goal is "it must be entirely within this ring to count" rather than just "I hit this ring".

I think it depends on the discipline, NSRA .22 in the post uses the outermost edge, but ISSF (Olympic rifle/pistol, for example) uses the innermost edge.

Isn't .22 a bit small for deer? I don't know anything though, so this isn't an informed objection just a question. Or were you just learning fundamentals of shooting before trying a bigger caliber?