Sorry for being late to the show on this one. Just wondering if your issue was ever resolved? I too have Radical AR-10 12.5” 308. I sent it back to them with feed issues and they put a different lower on and installed a double ejector bolt assembly. I had an adjustable gas key already installed for suppressor, so they returned it with my bolt carrier. It’s still sensitive to some magazines, but I’ve found that to be true of some of my builds also.
Take Care and Stay Safe,
Alan in the Amargosa Desert