Home Forums Hunting & Shooting Long Range Hunting Accuracy of Nosler Accubond (not Long Range) Ballistic coefficient?

Litz tested the LRAB offerings and found that many of them were way off of claimed BC. The 6.5mm version was within 1% of the claims, but the rest did not measure up so well. Wonder why that is?

Nosler has the reputation for overstating their BCs...

John

Speer too. Some of the old numbers on their match bullets and BTSP offerings were rather lofty. But to be fair, these were rather old numbers than they just never updated.

JPro,

As I already posted on this thread, Litz found the Nosler BC's for the 7mm ABLR's pretty close.

Per usual, many of the people now posting haven't read the entire thread. You and Hondo might read my post on the first page, which explains some of the reasons behind published BC's.

Yes, you did say that about the 7mm offerings. I've slept since I first read the earlier postings on the thread.

The 6.5mm results were the one I remembered reading, because they were very close to published figures, but looking at my snagged chart that he made, the 150 and 168 grain 7mm versions were not far off either. The .277 and .308 versions were not as close when run through standard 10" twist barrels.

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.

John,

I went back and read your thread.

IIRC, it was here on the campfire that someone shared this article a few years ago. I found it to be interesting as well.

http://www.dtic.mil/dtic/tr/fulltext/u2/a554683.pdf

John

John,

Thanks, I believe that was on the Campfire a few years ago. Or I ran into it elsewhere.

But my main points were:

1) Nosler doesn't ALWAYS over-report their bullet's BC's. It's hit-and-miss, if you'll pardon the pun. In fact some of the long-time listed BC's for Partitions have found to be just about right-on by Litz's tests, including the .30-caliber 200-grain, one of my old favorites.

2) There's a resource that helps a lot when in-putting data not just for Nosler bullets, but others, and it's BALLISTIC PERFORMANCE OF BULLETS.

Does the new edition include the ELD-X?






P

Interesting reading.

Rick Jamison did a BC test many years ago. He measured BC as he increased the powder charge/velocity. The BC varied with powder charges with one particular velocity giving the highest BC. BC below or above that charge weight were lower. That stuck in my head all these years. It is no surprise to me that BC can be different than what a company predicts.

I will also say that my long range shooting results with Berger's bullet have shown that their BCs are very close if not exact.

I once talked to Bryan Litz and he said unless you are using a chronograph worth thousands, there will some error in true velocity.

Add scope deficiencies with parallax and true MOA movement of turrets and it is no wonder some rifles don't shoot as predicted.

It is best to shoot that rifle at the intended distance to verify its performance. Some rifles that shoot tight groups at 100 have huge groups sizes at longer distances.

My neighbor's son shoots the 160 accubond exclusively in his 7 Rem mag and has done very well with some long range shots on big game out to 750 yds. The he uses the G7 BC of .244 / G1 .476 FOR HIS RIFLE. Your results may vary.....

I am not surprised by any of this....

With a lot of this shooting business I've found that looking at numbers and taking them as gospel usually leads to some form of disappointment.

I bumped into it yesterday at the range,which led to a blizzard of texts to my match shooting buddies about what's going on here?.... I will spare the details but it's back to the drawing board.

I've done the exact thing with a 7-08 and VX3/CDS, and 7mags and VX6CDS dials. I've never had any trouble doing exactly what you did out to the max distance on the dial with 140-160 AB's.

Azshooter,

It should probably also be noted that Berger's published BC's changed somewhat after Bryan Litz started working for them. Which doesn't "prove" anything one way or another about published BC's in general.

And the single-number BC's listed on Berger's website can vary from those listed in their loading manual, and from those in Litz's book BALLISTIC PERFORMANCE OF RIFLE BULLETS. The reasons probably vary, and might include ongoing tests, or tweaking of the design of some bullets, which just about all bullet companies do from time to time. Also, the Berger manual is now almost five years old, and a lot can occur in five years.

Nosler missed the 6.5 142 LRAB by a country mile, more like 20%....

The ballistic calculators (Hornadays) I find are close enough to get you on paper, if the paper is large enough. I normally start at 300 yrds, then go to 600. I correct if needed, and usually it`s needed. I also use the G1 number, as I`ve found the G7 to be too optimistic. But the point is the BC numbers are used as a starting point, tho you may find a print out dead on. My 7 Wby with 162 SST`s is one case.
I also make my own dial info, easy to change out if I use another bullet.

aalf,

The G1 ballistic coefficient for the 142 6.5 ABLR is just weird. One oddity is that in bullets of the same caliber, with similar shape, BC increases or decreases proportionally to weight, though that will vary slightly depending on minor differences in shape.

The BC of the 142 should be approximately 10% more than the BC of the 129 6.5 ABLR. But the listed G1 of the 142 is 28% higher!

The really weird thing is the G7 BC of the 142 is 12% higher than the 129's, which is about right.

I found the same thing this week; but Im not ready to toss the Nosler BC numbers( or the Hornady calculator) into the toilet. I came up short at 600 after making "assumptions" about the load, i.e.: I have not clocked the load, I am not rock solid on a 250 yard zero,and I am not going to make assumptions about how accurately this NF SHV is adjusting.

Knowing full well all of the above, I came up short at 600 after dialing 10.4 MOA a 600 and it was not enough.

So who can I blame? Mostly me for ignoring the basics.... but I will note the 7mm Mashburn Super is spot on and the Hornady Calculator says so. Mostly because the other stuff was worked out in advance.

Point being it seems lots of things can affect the outcome.

Litz figuered the G1 at .572



"My test results on the 129 and other LRAB's can be seen here: Nosler LR Accubonds: BC testing results
http://www.longrangehunting.com/forums/f19/nosler-lr-accubonds-bc-testing-results-137554/

I didn't have any 142's at the time of that test which is why they weren't included then.

My guess is that Nosler is testing their BC's over 100 yards, at high velocity. This is why their advertised G1 BC's are so much higher than the averages over long range. This is one of the problems with G1 BC's; what's technically correct over 100 yards and high velocity is practically useless over long range. You'll notice that they also advertise G7 BC's for their Long Range Accubonds, which are not nearly as far off from my test results because G7 BC's don't change as much with velocity. If everyone used their G7 BC's, they wouldn't be nearly as far off as they are with the G1's.

Another aspect that Nosler is suffering from is the reality that the longer bullets have faster twist requirements than what many shooters are using so the BC's in some cases are depressed even more thru marginal stability (there's more info on the in the post linked above). Nosler does cite recommended twist rates, but even they are slower than optimal in some cases and they're not shown on the bullet boxes and are difficult to find online."

-Bryan
__________________
Bryan Litz
Ballistician

I know, he posted on my thread. If I used his figure, I'd miss at distance.

Not saying he's wrong, but my results were/are repeatable......