This post is the first I've ever even heard of this "issue". I have one of the older style "original" 15-22's and after over 1,500 rounds through it, for the exception of 3 Remington Thunderbolt "failure to fire", I've had zero issues out of it.

P.S. I put those same three in my revolver and they still wouldn't fire so, it was the ammo..........not the gun.