12" is the same as all the other flavors of Derya and will run the same, though lighter and easier to swing around and Ballance for smaller framed people.
If you want them to run you need to keep them very clean. Specifically, the bolt face and extractor claws and firing pin and channel. The breach face, chamber and extractor grooves. You may also end up wanting to remove the left extractor claw. It helps with feeding and extracting reliability. Season to taste on that one.
.22's tend to crap where they eat and the Deryas are very sensitive to this so cleaner is better. If you put it away dirty and come back to it in a couple months it will
Possibly/probably cause you some issues.
Also, remove the buffer tube and install a toonie between the rubber bumper and the tube. This will help eliminate certain jamming issues and completely eliminate the chopping of the bumper.