This is an old thread but I am posting because I had a really hard time finding information on BAR accuracy. I have a BAR Safari with BOSS chambered in .300 WIN Mag, purchased new. I mounted 4-20 Burris Veracity FFP scope on it. I bought this rifle because I wanted a large magnum for longer ranges elk, mule deer, etc where I live in Idaho.
I am shooting Barnes TTSX in 165 gr. from the bench, I adjusted the BOSS weight system and could see the group size change, all the way up to 1.3 MOA. When I found the best setting (.30) I was able to get the group size to .6 MOA.
I have never had a jam, have used this for hunting in quite a few conditions and have put a couple hundred rounds through it practicing. I clean the barrel after each shooting with Hoppes solvent.
I have saved brass and planned to reload for it but likely will not bother due to the accuracy it has with factory ammunition. With accuracy at .6 MOA, this is an ethical 500 yard rifle. I killed my mule deer last year at about 400 yards, laser range verified.
The fact that it is semi auto, relatively heavy, and has a muzzle brake really helps tame the recoil. I use the rifle for extended backpacks hunts as well, despite the.
I think most people who hear they were inaccurate were from shooters who didn't know they had problems with scope mounting, barrel cleaning, ammo, flinching, etc.