Was playing Murder on Eridanos and discovered a Dead-Eye Assault Rifle III, don't remember exactly where but it was in the later stages of DLC.  Modded it with a silencer and Tinkered it up a few times.  Killed the Queen and went back to complete quest with Helen and ended the play session back on the Unreliant. 

The next day started the game up and my Assault Rifle III had turned into a Sentry Sabre Mk 3!  This occurs on all 8 of the save games after I discovered the rifle.  Unfortunately the next previous manual save was 4 hours earlier.

The Rifle III was probably behind one of the doors with a 105 Lock requirement so not to many people would find it. 

 

Having replayed from before the above bug, completed the DLC and I now have an Assault Rifle III and a Plasma Rifle III, both of which were obtained from the backroom of the store at the spaceport.