Love the "Swede"
Sounds like you do not reload, so I would suggest a 140-160 factory load.I feel either will work on game up to and including Moose. Try various loads to see what shoots best in your rifle.
As stated above, please have rifle checked to see if in good condition, and a reliable 'smith can tell you strength age type of action used to make the rifle you have.
The 6.5x55 is a great cartridge, but some of the early actions for which it was chambered are not very strong.
Hope your son shoots it well.
