I have a buddy that does aqua transfer. It is fairly durable, but it's still a base coat / clear coat type product so it will scratch, wear, etc (especially if they cut corners and skimp on the clear).
I also have guns that have been Cerekoted. The stuff is damn near indestructible, but unless you are willing to shell out more than you paid for your gun, you won't get anyone to spray a pattern so you'll have to go with a solid color.
If you're not in a hurry to get it done, I may have a better solution for you soon. Late in the season I bought a Stoeger M3500 in black matte. It rusts just from the moisture in the air! I've been talking with both my buddy that does aqua transfer and Cerekote about dipping the gun first and top coating with Cerekote's matte clear product. The clear can be applied over paint but Cerekote engineers are not sure how it will respond to fresh paint or if it should be clear coated first... Today I got a call from Cerekote and they are now suggesting a method using a solid base flash cured, then aqua transfer, then cure. They claim it will draw the paint into the base, sealing it during the cure.
I have written up 4 application methods and we are planning to do each on a test piece then get after them with steel wool, sandpaper, etc to see which stands up best. I'll post up results once we get it completed. However I have a crazy schedule for the next few months so it will likely be late March or April before we get to run the tests... (hence the "if you're not in a hurry')
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