Jim gave you the history very well. they also smeared Mobil Chassis grease on the Cupro bullets (has a lot to do with the "low # 03' myth")
Buy the rifle, clean it out with Wipe out, shoot it (forget break in BS) until it stops grouping well, then get out the wipe out again.
"More rifles have been ruined by cleaning than by shooting."
Marlin XLC 270, first 5 shot group out of the box after Wipe Out, glass bedding action and free floating barrel.. Never been cleaned again yet.