Kenny: you need a wall thickness gauge, and some practice therewith to be sure your numbers are reproducible.
Here's one
https://www.brownells.com/gunsmith-tools...auges/index.htm

I appreciate your effort and enthusiasm, but the gun should not be used, with any load, until some effort has been made to assess the barrels.
Someone with a bore scope also needs to check the bores for pits and erosions.
Please see
https://docs.google.com/document/d/1ZIo0y746UsSRZIgRuuxwAbZjSBHitO_EanvwLYc-kGA/edit

The '13" indicates a bore between .710-.718 so the barrels appear to be in original specs or very lightly honed

https://sites.google.com/a/damascusknowledge.com/www/home