The original poster asks for "acceptable failure to fire" with cheap .22 LR ammo. Maybe I'm missing the point here as many responders have their own perfectly acceptable approximate figures as to failure rates.

I shoot only CCI Standard Velocity in a number of handguns and rifles. I buy it by the case of 5,000 from Target Sports and have for a good while; no shipping cost and no tax.

A few months back I had one round that didn't fire with the first pull of the trigger in a handgun. Worked the second time. In an all the years I have used this stuff, that was the first time I recall such an incident and I've been using it in fifteen, maybe twenty guns. I can't attribute the initial failure to the gun or ammo, because I simply don't know.

This hasn't exactly shaken my faith in CCI SV as I recently bought another case, but the fact that it happened at all really surprised me. Since no one knows exactly what their failure rate is, I'll join the crowd and estimate mine as one in several thousand. That's one too many.