This truly is the MOAD!!! 13.5" sounds right. It looks thin based on the amount of res-c left around the tang.

A challenge coin is exactly 2" in diameter. I don't think 15.5" is acturate. I have a picture of my R9 that makes it look 15" because of the angle. As others have said, the file name is 1311. Makes perfect sense.

I like Randy's idea of putting my own regulator handle on one.

I'm thinking this is 3/16ths SR101 (I want SR77, but I won't complain). Going to be a fantastic machete!