Any information or advice?

https://www.fivesevenforum.com/index.php

Seems like a less common round. The link is a dedicated 5.7 forum. It’s not heavily active, but a wealth of information.

A few years ago I got started with the 6.5 Grendel, a dedicated forum had a bunch of info.

I’ve since backed off the Grendel some, haven’t divested yet though.

Thank you, I just saw one a few days ago and am very impressed. May push me into the plastic guns, but time will tell. In the mean time will just suffer along with my P210 and S&W 952.

I'd researched this in the past and much was said about the coating that FN uses on their brass. Some proprietary dry lube that helped the rounds cycle thru the P90 50 round magazine. It was also thought to aid in extracting fired brass. Reloaders were doing a lot to try not to disturb that coating, which can be stripped off by normal case cleaning. I'm not sure if that is a concern for the new non FN brand guns out there now.