I have read of many owners being happy with the accuracy of their A-bolts. I have a friend that has two, a 223 and a 300 WSM
. Both have the BOSS system. He can buy cans of bulk 223 ammo and fine tune the groups with the BOSS. His 300 WSM does the same.
I recently made his 300 a LR load with the 230 gr target hybrid. Got decent vel of 2720 fps. We shot it out to 500M and it shot just fine. Can't tell you if it would work for longer distances. It is light which doesn't help with longer shots than I mentioned.
If there was a flaw with the A-bolt it is the fact that it doesn't allow removal of the original barrel without the potential of damaging the action. As a result you won't hear of guys customizing it other than minor cosmetics. Perhaps others can join in?