I have the Barrett 99 currently with a Leupold Mark IV 6.5-20x50.  I also have a Nightforce Benchrest  in a 12-42x56 configuration.  A rep from Nightforce told me that the benchrest model is not as robust as the NXS series scopes and strongly recommended not using the benchrest on a 50.  Anybody using the benchrest mdel on their 50??

I have the same scope (12-42X56) since 1999 and it is still working.  When I started shooting 1000 yard matches about 10 years ago the NXS series was not out yet and most the people at the matches where using Night Force bench rest model scopes or Leupold MKIV scopes, it was about 50/50.   I have 3 NXS models also and have had to send 2 of them back for repair (one had to have the front lens re-bedded and the other had the front lens replaced, started to look not as bright or clear as the others) but the benchrest model is still going strong. Both times I had the scopes back with in 10 days of sending them in for repair.  They also did a turret upgrade on my oldest NXS free of charge when sent in for re-bedding. They have great customer service.

Ed

LOTS of FCSA folks are using Nightforce Benchrest scopes on 50's.  LOTS.

Only downside of the Benchrest series Nightforces is that they don't have much elevation adjustment.  The 12-42 really doesn't have much.  So don't plan on using it without either a sloped rail or sloped rings and you are unlikely to be able to zero at 100 and 1000 yards with the same mount setup.

-David
Edgewood, NM

Well, I went ahead and sold my Nightforce BR and have an NXS on the way (12-42x56).  The higher power only has 45 moa adjustment but I will have it mounted on a set of adjustable Barrett rings.  According to my calculations, if I can get 35 -40 usable moa adjustments out of the scope, I can get out to 1200 to 1400 yards with 750 G Amax, zeroed at 100 yds.  In addition, the new scope will have the NP-R1 reticle which would allow BDC of an extra 20 moa.  
Which brings up another topic.  Barrett doesn't make the adjustable rings anymore and instead appear to be selling the fixed slope one's.  I can only surmise they were having issues in the field with the adjustables not holding their adjustments when subjected to the percussions of the 50.  Having said that though, I've had this set on my 50 for three years now and 200-300 rounds sent down range with no issues of them coming loose.  Anyone else still using the Barrett adjustables?