Try closing the barrels with a strip of paper between the barrels and the balls. If it closes, try two strips. Typical paper is about 0.002" thick. BTW, I'm sure you meant 0.005" for your gauge strip. As a general suggestion, 0.004" is enough off-face to need fixin'; not that the gun is likely to blow up, but because it is going to get worse quickly.

You can also try the paper strips between the hinge pin and the "hook."

DDA