I came across a PDF, with no date or author, about the history of the Chinese M14 clones. It is a very interesting read!
UPDATE: H2O MAN in the comments below let me know that the text comes from “M14 Rifle History and Development” by Lee Emerson. Thanks H2O MAN.
A persistent rumor states that M14 rifles produced by the People’s Republic of China were reverse engineered from enemy captured M14 rifles in Viet Nam. China North Industries Corporation, known as Norinco, is reported to have produced M14 rifles by the early 1970s. The story continues that 100,000 Chinese M14 rifles were produced for an armed revolution in the Philippines. In preparing for this work, the author interviewed a very reliable source with extensive firsthand knowledge of Chinese and Taiwanese production and export of small arms was interviewed for this work. This gentleman wishes not to be identified. He is referred to as Other Source # 12.
Chapter 6 contains the History of the Chinese M14 Clones. The PDF can be downloaded here.