I don't know if this has already been mentioned, but the recent "Stuck grip" thread reminded me to share this.
A while back I bought a "Dr. Mom" otoscope for about 15 bucks. It has been really handy to inspect barrels and troubleshoot tips while they are still on the weapon.
It would be handy to spot a jammed washer in the grip as well.
http://www.drmomotoscope.com/
I am not Dr. Mom, nor is she my mother, but this is a handy armorer's tool.
Paolo

