Sorry, don't recognize it but it AIN'T a Model 54, although it is just possible that someone has used a Model 54 barrel as a blank to re-barrel it, and left the markings readable.

To me it looks like a German or Czech rifle of modest means, possibly retailed by someone like GECO. Some of those are very handy little guns; others are of marginal quality and strength. Might well be a .22 Hornet. We need markings.