There is some information about 12.7 mm AP bullets in the Russia's Arm's catalogue:
http://www.rusarm.ru/cataloque/land_..._for_89-92.pdf
The AP-I-T BZT-44 was introduced some time before 2001.
Several countries manufacture AP ammunition for the 12.7 mm HMG. The Chinese have been using a APHEI bullet for their Type 77 HMGs since December 1995. It will penetrate 10 mm of hardened steel angled at 30 degrees at 800 meters.