The 1:38 twist of the Marlin wont stabilize the heavier, say 265,300 grain and up bullets AS WELL AS the 1:20 of the Ruger bolt gun.This is not to say that you can't shoot the heavier bullets in the Marlinwith some sort of comfort as to accuracy.
The Marlin is twisted for the 240 grain bulletprimarily.
If it were I, I should like to shoot the heavier bullets out of the Ruger.