.22 WMR doesn't work well, at all, in blow-back actions.
Pressure is too high, with too much bearing surface.
The people that I have known, that had any kind of .22 WMR autoloader (other than the AutoMag II and PMR-30*), had more problems with bolts battering the receiver, rims getting torn the by extractor, cases splitting, and cases rupturing, than anything else that I've ever seen.
*The AutoMag II and PMR-30 use special chamber designs to reduce bearing surface in the chamber, as an ejection/extraction aid. It helps, but doesn't completely solve the problems inherent to the concept.
It's just a bad combination.
One of the problems is the fact that every .22 WMR ammunition manufacturer optimizes their ammo for a different purpose.
CCI, for a very long time, considered .22 WMR to be a handgun cartridge. As such, it was optimized for barrels of approximately 6-10".
Winchester, on the other hand, always considered .22 WMR to be a rifle cartridge. So, they optimized it for approximately 14-16" barrels.
And the few other companies that offer the ammo, like ArmsCor, fall somewhere in between - but usually favor the 'handgun' approach.
(Very few companies even load .22 WMR. Over 80% of the current supply is manufactured by CCI, for one of their ATK brands or under contract by Hornady, Remington, Fiocchi, etc.)
Stick "handgun" ammo in a semi-auto rifle, and you're more likely to have extraction issues.
Stick overly-slow "rifle" ammo in it, and you're more likely to have ruptured cases.
Stick something in the middle in there, and there's no telling what problems might show up. ...Or if it will run like a dream.