Bob, try 1/2 oz, or two 10 penny nails if the wing is foam. That's what has worked for me.  the attached picture is of a plane I took to Brodak's last year but didn't fly because of some leg problems.
Joe

As a result of quite a bit of experimentation and test flying, I ended up with 2 1/2 ounces on the "Sniper". Of course this is for prop hanging slow flight. I would permanently install at least 1 to 1.5 ounces, and also have a box for more, or at least be prepared to affix more to the outside of the model.

Thanks for the info, didn't make the same mistake I did on the big FJ and build the tip weight box too small. This is the tip weight box in the FJ-4-15 with a 1 1/2 ounce hunk of lead dropped in. Plenty of room for whatever it takes  

     Hi Bill, you are so right about 2-1/2oz for tip weight in a .15 carrier plane that you plan to hang. Although the lines are lighter, the wings are shorter so it seems to take more weight out there than you would think. Eric