1st plug 181 into your plug gauge equation which is for 7.7X57R or .303 British. Then plug 248 in and it should approach a 0.26"-0.27" value which with about 0.01"+/- with rifling is going to approach 0.28?" Check the values as I may have miscalcuated but I'm doing it on a consistant basis.

Yours just by the marks, and not the date, is a post 1912 which checks with your 6,13.
Kind Regards,

Raimey
rse

Last edited by ellenbr; 12/17/08 01:29 PM.