I worried about the same thing. I got one because my older marlin made microgroove didn't shoot cast well.

But the new one shoots much better than the old, cast or jacketed. I did have a burr in my ammo tube, that jammed after 3 rounds. They sent me a new tube. That was out of round and about 1mm too long. They wanted me to send back the gun. I said screw it, and machined it down and straightened it out. Good news is it shoots well.