The small-cased Marlin cartridges appear to be pretty good as long as factory ammo is used. I'm not too enthusiastic about trying to match the factory specs with handloads in the small cases they've adopted. The 308 (or 307) Win will work through the action. I think by using a small case, they could be to trying keep people from using 308 Win loading data, which may (or maybe not) stress the M336 action.

My gut feeling is that for us handloaders, a wildcat like the 338#2 JDJ or the 375 JDJ would be a better approach. In fact, I like the ballistics of my 14" 309 JDJ Contender, and think that would be an ideal Marlin chambering. A 20" barrel would give the cartridge "legs."

Oh, and before anybody chastises me about pointed bullets in tubular magazines, there is an easy cure. Don't do that.