My boy, who is now 15 yrs and 140 lbs, went from a 22lr to a model 1893 Spanish carbine in 7x57 @ 12 yrs old and 100 lbs.
I must confess that I handloaded his ammo to 30-30 class, 160 grn bullets @ 2400 fps.
The stock was bubba'd when we got it, and fit him very well.
The military sights are actually very decent for a military rifle, much better than my German 98.
He still has the rifle (and loves it), but now it wears a Boyd's Laminate sporter stock and a Bold trigger,
he can manage 2"-3" @ 100 yds (young eyes) from a kneeling or seated shooting position, which is plenty good around here.
Most shots here are less than a hundred yards.
I do load full power loads now (for an old mauser @ 44,000 cup) 160grn @ 2700fps and he shoots them just fine,
I find his rifle a pure joy to shoot, and he doesn't want it scoped,
we also have a Savage Model 99 in .300 Savage with a scope if he needs a scoped rifle.