Seems to me a .410 in a .45 cal. barrel would be terribly inefficient and ineffective.
Powder gas and pressure would immediately escape, bleed off power, and blow your shot pattern to hell.
A shot load would probably be more effective than a rattling, tumbling rifled slug, but either way, you'd need to be within spitting distance, just a very few feet for any decent effect.
The stubby little grip on that gun looks like it would be brutal on your hand.
I've never shot one of these guns, but from the looks of it I don't think I want to try.
I'd rather have something more pleasant to shoot. The more you use a weapon the more likely you can use it effectively.