Interesting discovery today.
I vacuum tested a sadlak Ti coated piston , non grooved, in 6 different 2009 and newer gas cylinders and it passed the test on all 6. Then tested on a couple older cylinders and failed on those. So I tried my collection of USGI pistons, all are used takeoffs from prohib M14 rifles, and all 7 passed the vacuum test on the newer chinese cylinders, on the bench anyways.
This is by no means a claim that sadlak pistons will function optimally in the newer chinese cylinders. Some comprehensive range testing would need to be performed first