Well, I took it to the range today.
Using Wally world .223, I was making ave. 3" groups at 100 yards. I been able to do 6" group with irons, so I am not to impressed. Perhaps I can do better job with better rest or a bipod. Still it was accurate enough to make soda can dance at 100 yards.
Interestingly, B&T scope mount works as a brass deflector, and shells are now exactracting 2 o'clock and 15 feets to the front consistantly. No longer are the guys on my right being showered with hot projectiles. This doesn't seem to cause anyproblem, and there is slight brass streak on the front of the mount right behind the ejection port, which simply wipes away.
Unfortunately mount is about 1/4" too high to clear ACOG channel that allows use of iron sights.
I also haven't tried BUIS on TA01NSN, but I heard that it is difficult to use.
TA01NSN with its very clear sight picture, allows me to take precise shots. Though not as fast as TA31, I am not sure I would like rather large donut of death thingie. For BAC's CQB usefulness, I would probably replace TA01NSN with Reflex or EoTech.
ARMS & B&T mount combo is excellent, and scope does seem to return to perfect zero at 100yards.