Originally Posted by notorious
As long as it doesn't hurt the barrel by having a bullet that is .003 smaller "bouncing" around, it sounds like good, cheap fun. Another thing, how would it seat into the barrel properly?
.223 Remington/5.56 Nato and .22 Long Rifle both use .224 diameter bullets.
The problem you will encounter is that the rifling in the barrel may not be slow enough to accurately stabilize/not destroy the .22LR bullets.