Well, now, we have a 13 year old, he's a pretty big boy. He even wears bigger shoes than I do. It would depend on his size. We had him to the range when he was 12 and he was doing just fine with his mom's .380. I think she's gonna wind up with 9mm pretty soon, and if I ever get around to extending the ramp on the MkI I'll put him on that for plinking. Thing is, the grips on that are a lot bigger than any of the .380s here, and the .380 was fitting his hand well.
I'd highly recommend a browning buckmark. A little weight isn't a bad thing if someone is new to shooting. While there is such a thing as too heavy, there's no way this is anywhere near that point, it's just easier to hold steady.
On days when I'm feeling gutsy, I take this out to the 100 yard range with 2" steel swingers on a rack. It's not too terribly much effort to connect more than 50% of the time.
While people have good luck with ruger mark series pistols, I've not shot a recently made one that runs reliably. All the issues I had with them were related to the loaded chamber indicator, which they might have subtracted or changed by now. Meanwhile my buckmark has never had a feed or extraction problem before, I have had a handful of duds in bulk packs and a couple undercharged rounds that failed to fully eject, but with any decent 22lr I haven't had the first problem.
The serial on the MkI from my dad traces back to 1955 Only trouble with it is the feed ramp is too short and it catches HPs, which is most of what I have. They make them longer now, I just have to take the MIG to it.
22 45 for the win. I still have my MkII Government model from my Military shooting days. I was in when we still had 1911s, and that was our 22 training weapon. When we switched to the 92, we did not use them as much due to the difference in the trigger sa to da/sa. I am 'considering' getting rid of it, but just cannot seam to..