I had a chance yesterday to browse though a local gun shop and got into a conversation with a fellow shooting enthusiast. we started talking about how to get components for the not so common calibers and casting bullets for them. this guy I'm guessing doesn't visit here and was saying you cant shoot cast bullets in marlins microgroove barrels because the grooves will fill with lead. he was absolutely sure about it. and he wasn't a youngster but a retired guy who has been hunting all his life. I tried to straighten him out and explained how sizing bullets a couple thousandths oversize , using a good lube, a good alloy and a gas check bullet design, keeping velocity at 30-30 or 35 rem speeds will allow him to shoot all the cast bullets he desires in just about any rifle microgroove or not.