I might also note that the BC of the one standard AccuBond I've tested at longer ranges, the 140 6.5, is pretty close. I acquired a 4-12x40 Leupold VX-R in 2015, and after determining the clicks were accurate and repeatable, decided that it was time I tested a CDS dial. (For some reason had never done that, instead just making my own dials with masking tape.) After thinking about it for a while, I put the scope on my 26 Nosler, partly because I had a bunch of factory ammo loaded with 140 AccuBonds that shot very well, and chronographed very close to the advertised 3300 fps.
Nosler's listed BC is .509, which is very close to the average of what Litz lists for the 140 AB's G1 BC's for velocities from over 3000 fps down to 2000 fps, approximately the velocity range of the load over 600 yards. So I ordered a CDS dial, listing the factory BC with environmental factors about average for hunting conditions where I live, and tested it on a calm day at just about those conditions, 35 degrees Fahrenheit at 4000 feet above sea level.
After sighting-in at 200 yards zero I started shooting. The range where the test took place goes out to 1100 yards, but the limit of the one-turn dial is around 650 with the 140 AB load. It was basically dead-nuts out to 650, with no tweaks to the dial, so apparently the dial agreed with the Nosler/Litz BC.
Now one of the factors that goes into all this (as stated in my post on the first page) is that BC varies with velocity AND rifling twist--but most companies list one simplified number. The BC's Litz lists on the Internet are also simplified, the reason I instead used the info from his book, BALLISTIC PERFORMANCE OF RIFLE BULLETS. It includes range-tested BC performance at various velocities in 500 fps increments, from 3000+ down to under 1500 fps, so it's easy to come up with an average BC for the ranges you'll be shooting.
However, many people keep believing that ONE ballistic coefficient number, usually a G1 rather than the G7 more accurate for long-range bullets. A single G1 BC simply will not serve for all longer-range shooting, but better information is out there for shooters willing to pay for it. Most, however, expect to find free, and much shorter, answers on websites like the Campfire.
For those not afraid to spend money for more complete information, BALLISTIC PERFORMANCE OF RIFLE BULLETS costs $54.95 and is available from
www.appliedballisticsllc.com. Which reminds me, I need to order the 2nd edition myself, which includes more bullets in a wider range of calibers.
