Micro groove is a very shallow rifling and shoots best when cleaned regularily. Plain HOPPE'S products work great.
Typically, a Marlin with its 1-10 twist will stabilize the 170 grain bullet variants quite nicely. I've handloaded Hornady 180 grain round nose bullets with hand-filed flat nose for safety. They shoot amazingly tight. But my best groups come from Speer 150 grain flat nose bullets but I can't explain why this is so. I'm not an engineer. I read somewhere that FEDERAL Fusion ammo features Speer HOT-COR bullets.
Fire up the grill! Deer hunting IS NOT catch and release.