Thanks Dallas. Feel stupid now after doing some research. Looks like I am lucky I didn't try it the other way around - 308 Win round in a Marlin lever action....May have ended a good day on the range early.
To others, learn from my F-up. In the "ammo scare of '13" a lot of local shops out here are selling ammo in mixed boxes. It was labeled 308 Marlin Express but after seeing a "new" box online I see that it says "lever' action and has (small) print that states it may require a change in follower to properly load all rounds. Still, it dint clearly state that it was lever action / rifle specific. Blame myself for buying before researching. Just grabbing anything that says 308....