Sorry for the late reply... had not looked at this tread in a while.
Quite frankly no i never checked the caliber...
I might have tried a dummy round in it but it's been so long i don't really remember...
Since the start i had no plan to keep that barrel on the rifle so it never came to mind.
The restoration updates are on the ''Pattern 1913/1914 and M1917 Rifles'' section of the forum, if you want to have a look.