I’m not aware of any on the market. What would be a good piston system to build one out? I don’t think PWS sells their system on its on. Which is my fav besides LWRC. SYRAC was one I had my eye on for awhile. Seems they are out of business now.
I have an Osprey Defense piston kit in a 6.5 grendel build. I am rather fond of it.
They are located here.
Before I got mine, I did a search here, and failed to find anything negative about them. The few folks that had experience with them were pretty positive. I guess you can add me to the list of positives now.
I wish you luck with your search. Whatever you choose, let us know how it works out. This place could always use some more pistons.