I'm guessing the hose washer is vulcanized rubber, silicone or nylon. The Glock frame is a glass filled polymer plastic made to resist solvents that would bond. These materials can't really bond to each other. What you need is an adhesive that bonds separately to each and is as strong as the hose washer.
After some time, the hose washer, if rubber is likely to become brittle so you probably want a strong but not permanent bond.
For this, I would suggest clear silicone sealant. You buy it in the paint department at any big box hardware store. Silicone sealant is used in construction for everything from setting windows to applying ceramic tile counter tops. You normally buy a tube of it for use in a caulk gun but it is often available in smaller size tubes like tooth paste. You might even be able to find it as a glue stick for use in a hot glue gun. Wrap it with vinyl electrical tape that won't leave a residue on the frame until it sets up, about 24 hours.
I would prepare the surfaces using 6-800 grit sand paper on the gun frame and lacquer thiner on both surfaces.
‘‘We, the People are the rightful masters of both Congress and the courts — not to overthrow the Constitution, but to overthrow men who pervert the Constitution.’’
— Abraham Lincoln
Last edited by Mr Lucky; October 15, 2010 at 01:40 PM.