I have a Howa Alpine w/20" barrel. It's a dream to carry and hunt with. I load it with 120 gr. NBT for Whitetail's in Oklahoma. I've had great success with Ramshot Hunter, IMR-4350, H4350, & RL-17. I've had good accuracy with all powders. RL-17 & Ramshot Hunter gave the best combinations of accuracy & velocity. I can exceed 2800 fps with either powder in the 20" barrel and have repeatable 1/2 MOA accuracy at 100 yards (3 shot groups as the barrel is thin on this lightweight rifle.) Have taken several feral hogs with this rifle and the 120 gr. NBT and they perform well at 2800 fps muzzle velocity. I believe you and your son will greatly enjoy the 6.5 Creedmoor. The 140's shot great from my rifle but the velocity was around 2550 max with my short barrel. The best factory load I've used is the Nosler 120 gr. NBT load. Averaged 2803 fps over my chrony and shot under 1 MOA consistently.