What is the depth that a company has to imprint the name and serial number on a frame? I have a bunch of Cooey .22s with no company serial number just the CFC stick on things, can I use an electric pencil and engrave the number on the gun or do I have to stamp it to a certain depth. I read somewhere that the U.S. has to have the number stamped , and the name can be electrically etched, does Canada have a similar rule/law.