I don't know the answer, but I do know how to find the answer.
Find the members list on CGN, find 'Different', find his webpage, download his amazing 400+ page electronic book on the M14, and start reading up on Chinese M14 rifles. I remember there are tables of equivalencies and other specification details.
If you don't find your answer there, then google for M14 drawings or blueprints. There is a website (standard internet truism) that posts (posted?) copies of the US Ordnance drawings for the M14 receiver. The thread dimensions are certainly shown there. But it is a lot more research.
Next question, why are you asking this question? Because ... there is a lot of stuff hanging on an M14 barrel and each of those surfaces is critical for stock fitting, accuracy and semi-auto functioning.