I have a 18” extra barrel is the only reason and I figured I’d have it spun up. Primarily will be run suppressed. The lighter 7mm bullets are much better ballistically for sure. I’ll probably run the 137 or less hammer in the 308 and the 7 Hammers as well in the 7-08.I have no qualms shooting elk with a 7mm-08 TSX factory load that would be solved by shooting a 308. They're just so close it's not worth the expense to switch.
If you reload you can load lighter bullets with a slower burn rate powder with the minimum load recommended by the powder manufacturer and that will tame the recoil some. A brake will lessen the recoil tremendously but he'll need good hearing protectionIs there something in between a 7-08 and .308? My son wants bigger, but the .308 has too much kick.