Actually the 307 was intended to produce 300 Savage numbers out of the popular 94 action. Only it came along about 20 years too late. As has been stated basically a rimmed 308 case loaded to a lower pressure. On average about a whole 2-4 gr lighter on the charge depending on the powder used. Winchester's are the only guns to have made it into circulation though not many, Marlin did list it in their catalog but never produced any. The only factory loads found now are winchester's 180 gr PP, they kick harder than a 180 gr pill out of an 06 IMO. I load 150's and 170's. I'd say get him a box or two of shells and maybe a Pachmayer Decelerator recoil pad. He'll love you for the pad alone.