Mark,
The 397 is .177 and the 392 is .22. The pumpers are less hold sensitive than the springers. You do have to pump them multiple strokes. Even with iron sights they are capable of "minute of can" accuracy in the backyard. I wouldn't give up on the X20 yet. Have you shot it with just iron sights? There can be a lot of reasons for accuracy issues and a loose scope connection is just one of them, your hold is another, etc, etc.
Last edited by hangmancreek; 04/13/15.
