I'm not a gunsmith nor do I play one on TV.
But I do recall an episode of American Guns (Gunsmoke?) where they actually built from raw stock a replica Colt SSA for a preacher that was a SAS member.
I call that doing more than changing parts and assembling.
NRA Chief Range Safety Officer, Home Firearm Safety and Pistol Instructor
"There are three classes of people: those who see, those who see when they are shown, those who do not see."
Leonardo da Vinci