dunno if anyone is game to try this........
There is an Aussie made specialty coating - available in several colours.
It is used as a coating for cast lead bullets.
"Hi Tek" bullet coating,
Email: jandmspecializedproducts "at" gmail "dot" com
Easily posted - not dangerous goods as it is in a safe powdered form.
requires mixing with acetone for application - and curing for a few minutes in an oven, usually needs 2 - sometimes 3 coats.
When you think about it - this stuff needs to stick to lead, take the heat and pressure generated by the burning propellant, as well as the friction as it passes down the barrel @ up to around 2500feet per second.
One of the tests used for the coating is called the "hammer test" - you take a coated lead bullet, place it on a solid surface and smash it with a BFH.
If the coating comes off it has failed.
I have recovered fired projectiles from our range - and even with impact damage - most of the coating has stayed on.
It should be good enough for a pair of sunnies
Give your local pistol / rifle club a call - ask if anyone there uses the HI-TEK bullet coating, see if they will do them for you.
probably cost a carton
If you have no luck finding someone - sling me an email as I might be able to help finding someone near to you.
stephen