BC's are too low and too much velocity is required to open them. In other words, with the low BCs and high velocity requirments, they arent optimum 800+ yard bullets. We use bullets that will open up at 1500-1800 FPS AND hold together at 3000+. Barnes will hold up at more than 3000 FPS but will not open reliably at 1800 FPS. Plus they are expensive and it is hard to find a load that they will group (in most rifles).
As far as them not being accurate past a given yardage is not true. Every bullet has optimum velocity and twist ratios. If you violate those paramiters, you will have loads that are accurate up to a given yardage and not worth a crap past that yardage. On the flip side, you can have crappy accuracy at closer yardages and phenominal accuracy at longer yardages. You can also have excellent accuracy from 100-1000 yards as well. Figuring out these optimum zones is tricky. It takes massive amounts of experimentation with YOUR rifle and an assortment of bullets at a wide range of velocities to really figure it out.