my ISSC M22 Always misfire, shell Ejection issues.
I use CCI minimag 40gr
Your best chance at a consistently reliable .22 pistol is to buy a Browning Buck Mark or a Ruger.
Dump the ISSC and get a Ruger, you will never have an issue again.
The PMR30 in .22 WMG was very very reliable. From my experience anyhow. I know you asked for .22LR.
You could run that trigger as fast as you could and it would just keep going.
I could never justify the 900 cost of a mostly plastic Kel Tec range toy in 22 WMG lol But I shot my friends quite a bit on multiple rage outings and I was very impressed with how well it cycled and shot as far as reliability.