If you don't know how to age a gun leave it alone.
Most "aged" guns don't look old they just look aged.
I think the "aged" idea is simply something to sell to people who like the look. I used to think it was pretty neat but I outgrew it. I have a rifle I have likely carried 100 miles or so on foot hunting and it does not look aged. I did scratch it up a little more last time out but I doubt many hunters in the 18th-early 19th century scratched their rifle on a S&W hammer spur.
The barrel is plum browned fairly thinly and this is wearing pretty thin. But it took the shine off for hunting season a couple of years back.
Part of the problem is we have little idea what the gun looked like when it was 20 or 50 years old.
Could have looked like RCA #81 just as easy as not, might have been nearly wrecked is 5 or 10 before the wood even got worn.
This rifle probably has 15-20 years use on it based on its suspected build date. It managed to survive unbroken but it has some wear from horseback use, likely from being slug from the horn and from use in general. Its impossible to really look at since its under glass. But you need to carry a rifle like this to appreciate what is being seen. Eastern guns would show a different pattern.
A lot of the serious wear seen on guns is from be transported in a wagon. Worn through into the rod channel etc.
But most folks never use a horse drawn wagon anymore, certainly don't haul a gun ready for use everyday and don't realize this.
End of break time.
Dan