You would have to look at the last photo in his slideshow to guesstimate 3/8" or 1/4".

Had to chuckle on the Model 4 with single hilt as a "Fighter".
_________________________
Buck Buchanan, RKCC #CM-16, RKS #1003
NRA LIFE
NMLRA LIFE
Authorized Randall Dealer
buck100_10x@icloud.com