I had to send an STG58 back to DSA for warranty work do to an improperly timed barrel.   Wow,
I had to jump through hoops with the first person I talked to about it as well as a bunch of long distance phone calls.  This individual basically called me an idiot and told me sometimes these rifle's sites have to be adjusted all the way to the end of their travel in order to zero them in.  They are battle rifles don't you know, you dummy.
Man, I own 3 FAL's, you would think I would know a little bit about them. (If I would have adjusted them any more, the site would have slid out)  Anyway, I finally talked to someone else about the problem and he grudgingly gave me a return authorization.  Any one else ever have any problems with them?