My first handgun I paid for, Dad bought, back in the 60s at about age 13 was a S&W Model 18 - aka K-22 Combat Masterpiece. 4" Bbl. plain ramp front and adj. for w. & e rear sight. A nice used one - search gunbroker -
may run $425-$450. S&W also just re-introduced this model but they're kinda steep but they'll last a lifetime. I have the MOdel 617 with a 6" Bbl.
and it's got the 10 shot cylinder.
Last year S&W also brought back the MOdel 63 "Kit" gun instead of the
medium (K) frame, like the 18, 17 and 617, the 63 is built on the small (J) frame - problem is the only one offered has a 5" Bbl. kinda muzzle heavy and not that handy. A used one could be found with the 3 1/2" Bbl.
Semi-Autos - Ruger .22/45 - it has the grip angle similar to a 1911 the basic inards are like the Ruger Mk II/III.
You might also consider buying a CZ 75B, in 9mm luger and get the Kadet
.22 LR conversion kit for it, aluminum slide, barrel, spring and mag.
How big physically are your sons?
There's also the Berreta 86 and the hard to find 86 Target.
The 18 sure taught me to shoot carrying it on the farm, with a 6 shot cylinder, rabbits, and rattlesnakes, etc.
Randall