Does anyone know why older shotguns have this feature?

[MelvinWalker]

They are round or oblong/round brass disc about the size of a nickel located underneath the buttstock...They are flush mounted with no nails and are usually in about the place where a rear sling swivel would mount...The two shotguns I have, (rabbit ear coach guns), would obviously never have a sling swivel installed.

Any ideas on this?

 

[gdogs]

For engraving your initials.

 

[MelvinWalker]

For engraving your initials.

Seriously?....I never would have guessed that.

 

[Muley Gil]

It's a spot to have your initials engraved.