The CG63 was made in 6.5x55, hence the 140 grain bullet. I think the Internet Search for a 140 grain 8mm is a wild goose chase.
Also in .308, which I once owned. A nice rifle but long and heavy.
I believe the OP has Something Else as I have not heard of an 8mm CG63.
I think it a hunting rifle on the Swedish Mauser action.
But we will not know for sure until and unless the OP shows us pictures.
It takes a trained description to identify a gun, pictures are more reliable.