Hello Florina

Welcome to the site

The best way to find out is try to fit a 16 gauge hull in the barrels smile

http://lcsmith.org/

http://lcsmith.org/shotguns/1913grades.html

CONDITION is very important and also ANY modification.

Take a look here and pay attention to the smaller than
12 gauge guns

http://www.gunbroker.com/Side-By-Side-Sh...e=1&Sort=13

ALSO you can request a letter on this particular shotgun
http://www.lcsca.clubexpress.com/content.aspx?page_id=22&club_id=43784&module_id=245742

Again, Welcome
Mike