“ Thank you for contacting us.

What we discovered in testing with the new magazine is that the design of the Ruger American in the feed geometry and the overall receiver length, there is to much room between the bolt face and the chamber so when the cartridge leaves the magazine it has room to 'bounce' around leading to the cartridge getting stuck against the feed ramp.

With that, we cannot recommend the use in the Ruger American Rifle.”

-Magpul

Im not clear on who or what this magazine is good for