Thanks to correspondent Ed Nash (he gave me permission to use his name after I had recorded the video), I have a number of really interesting photos and video clips of YPG (Kurdish) locally-produced anti-materiel rifles. Specifically, the Zagros 12.7mm rifle and the Şer Portative 14.5mm rifle. Both are made on a small serial production scale by the YPG using barrels from DShK and KPV machine guns. Tubular receivers and bolts are fitted to them, making effective single-shot rifles.
These photos are from the fall of 2015 and the summer of 2016. I am told that both types of gun were reliable and effective, and used substantially in combat against ISIS/Daesh, with their necessity decreasing after the YPG began receiving more air support from United States forces. These were not sniping rifles so much as anti-materiel rifles, used against walls, light armored vehicles (including VBIEDs), and other sorts of cover.
For more information on craft-built anti-materiel rifles, check these two posts: