Any coating adds a little "bulk" to the pieces. Some "bulk" may have to be later removed for the revolver to work correctly.
As a side note, on a 1911 handgun I applied Alumacoat to, a flake worked off the frame and onto the sear. I've already had 2 boxes through the gun and did careful prep work (including complete disassembly) before painting. The flake created hammer "follow" (the hammer dropped to half cock when fired). After removing the flake from the sear and hammer, all is working again.
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
Life Member NRA
Life Member NAHC
Former President of the ECPT (Eifel Combat Pistol Team)