This is incorrect. A maker of a firearm is not required to engrave the caliber or serial number. An example of a maker would be somebody who uses an eForm 1 to shorten the barrel of a serialized rifle they purchased with a 16 inch barrel. This is what
@Steelitall did. A maker only engraves the following,
The maker, (or trust)
City and state. (The state can be abbreviated to the official two letter code or spelled out completely.)
If you build a rifle on your work bench from unserialized parts from scratch you would engrave the information you listed. In this scenario you are the original manufacturer, not the maker.