Mine is the Rugur American Ranch Model. It uses any standard .556 AR-15 mags. Any mill-spec AR-15 .556 / .223 mag will work in that Ruger Model.
I use MagPul AR-15 mags in mine.

Don’t know which mags the Predator Model uses.

Check Ruger’s Website for that models Factory Specs:

https://ruger.com/

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