I had a Marlin about 15 years ago with the micro groove. Shot jacketed just fine, but my cast left something to be desired. After I sold the gun, I was told I was probably shooting too hard of a bullet at just over what I should have been trying as far as fps. I had a shooter tell me he got his to shoot just fine with cast, he made his bullets softer, and slowed the velocity down to around 1000fps. But like I said, I had already sold the gun.
I figure that I could pick up a used one alot cheaper than a new one, it would be easier for me to convert it over to a standard type rifling, plus I would like the looks of an octagon barrel. And then I wouldn't have to try and figure out if my bullets are to soft or to hard. Plus, I just like the idea of having something different about a gun. Like a custom paint job on a car or motorcycle. gypsyman