A very small, thin o-ring between the inside surface of the wooden grip and the frame metal will usually tighten up loose wood.
Also, you might wait a few days. If the luger and its wooden grips were in the dry heat of AZ State, they may just absorb a little humidity from the climate of their new home and might just become tighter all by themselves...
Regards,
Pete... <img border="0" alt="[typing]" title="" src="graemlins/yltype.gif" />