4V50 Gary is right about the military arms. The military of the olden days operated on total and utmost conformity, and if you weren't like the rest of them, well, you will be made like the rest of them.
But the 1700s to the 1920s was the era of the "custom jobs". Most fine rifles in the hands of backwoodsmen, hunters, and expeditioners were not military firearms. They were custom built by gunsmiths the majority of whose names are not remembered today, despite their hard work. So you would definitely have people who had rifles and guns built and tailored to their exact needs.