Tikka, first rifle calibers-recoil

[FEENIX]

Another vote for the 6.5! I started both my sons (now 31 in USAF and 28 in USMC) shooting at age 5/6 and hunting at 10. They started with a Carl Gustaf carbine with 18" barrel in 6.5x55 Swedish Mauser.

Happy safe hunting/shooting.

 

[Foundation]

I've been using a t3 in 308 the past five years but would probably go 6.5 for your son.