Briley Chokes - any conversion info?

[Richard59]

Ive a couple of Briley Chokes, despite searching am failing to find a conversion chart, does anyone know what the following chokes are in "English" (1/4, 3/8, 1/2 etc) thank you

Briley I/C
Briley MOD

 

[AW13]

This might help

Borrowed from:
https://www.theyorkshiregent.com/shooting/shotgun-chokes-explained-guide-markings-sizes-patterns/

 

[leighH]

I/C is 10" or 1/4

Mod is 20" or 1/2

Regards

Leigh