Ernest, I have owned four .22 mags over the years (rifles), three of which were Marlins. The last Marlin I had was not consistent, in that sometimes it would group very well, then suddenly it wouldn't. The most consistently accurate one I have owned is the one I have now, a Ruger 77/22 BMVZ.
One thing I have found with the .22 mag., is that accuracy has not been as good as what I would expect from a good .22 long rifle, but it is still good and acceptable. If you measure the .22 mag's accuracy against the long rifle, you most likely will be disappointed, or at least that has been my experience.
Still, I love the Ruger in the .22 mag.