Aero Precision is working to bring a new piston compatible version of their COP Upper to market. It will have all the same user configurable monolithic rail functionality that you have come to expect from the COP Upper but the new version will allow the use of various gas piston systems like those from Adam’s Arms.
The uppers will be available separately initially. Kits that come bundled with an Adam’s Arms piston system will be available soon. Pre-sales on the upper receiver alone will start soon with delivery coming sometime in April.
Check out Aero Precision.