It's the magazines that are prohibited. Has nothing to do with what gun they are in.
Pistol magazines are limited to 10 rounds.
Ruger 10/22 magazines fit in Ruger 10/22 Charger pistol —> therefore any Ruger 10/22 magazine with capacity greater than 10 rounds is a prohibited device...
This weird logic is why you can use a 10 round AR15 pistol magazine in a WK-180 and everything is fine according to RCMP super geniuses!