Shank diameter is 1.1" or so. TPI appears to be about 12.What is the shank thread diameter? Can you determine the number of threads per inch? What is barrel length? If you can post this info can confirm. May be for No4 Enfield T4 or could be for Parker Hale 1200 family of rifles. Markings indicate 7.62x52 NATO or 308 Win barrel proofed at 20 Tonnes providing chamber isn't dicked with.
Thanks, Ron. No other marks that I can see.Based on your dimensions this is for a Parker Hale L81 cadet action - Numrich has a ton of these for sale awhile back - std Mauser thread. Looks like both are drilled and tapped for a front sign block. any additional marking on the barrels?