I don't have experience with the Federal Arms or the CETME, but Century makes a good stainless receiver based on SW's design.
They bought the rights to produce the SW receiver some months ago.
Too bad Century can't modify a FA trigger pack to SA for ****.
If they could fix this one bug, the rifle would be outstanding straight out of the box.
I have an FA reciever G3 clone. It has a set of built in scope rails. I've put a lot of rounds through it and haven't had any problems with the reciever (the bolt, which is original H&K, is another story...)
It is the furthest from the HK91 original design, but it's sturdy and I haven't had problems .
Note that a wide forearm won't fit on the FA reciever - only the slimine forearms.