The idea itself is not new. Savage made one years ago, however hard to find today. The 410ga chamber size offers the opportunity for some rifles to be made into a 410. I think they are all good, really, but the important thing is choke size. For rabbits and grouse a 410 Full choke with shot size like 6 to make a dense pattern is important, but not too many bb's as like 7.5. But if you have a good dog with you to sniff out what you shot at, you can use bigger shot size than 6, or more open chokes. I don't mean to steer your thread into another direction, and lets keep it focused on the original question you asked.