Originally Posted By: JohnnyJohnson
Older ones that don't have the micro grove rifling are. Forget shooting cast bullets in your newer Marlins.
Please, put this old recycled gun writer balderdash to bed.
Size your cast bullets properly, which for MicroGroove means several thousandths larger than Ballard, and it'll shoot great. That means around .431" for 44Mag or 444, .460" for 45 Gov't. Since that's a couple thousandths larger than usual, some Gun Writers, using the usual undersized, over-hard commercial cast bullets, had the expected bad results of using undersized, over-hard cast bullets.
As bunnspecial pointed out, MG rifling has been replaced with Ballard from some cartridges, like the 45/70 and the 444, but it remains for others.
Quality on newer Marlins has been hit and miss. Inspect very carefully before taking it home from the gun shop.