Hornady 6.5 140 ELD-M BC Change?

[STOMP442]

So, I was working up a load for a client of mine and when I went out to do the ballistic validation I noticed that the BC for the 140 ELD-M was considerably lower than it used to be in the Applied ballistics app. The AB app is currently listing a G7 BC of .301 and a G1 BC of .587. This is much closer to what the old Amax used to be. I went with it and sure enough firing solutions were not working out well at all. I went in and manually changed my G7 BC value to what it used to be .322 and things came together like they were supposed to. Does anyone know why the BC values were lowered by so much? Have they actually changed the design or something and I am just using an older lot of bullets with a better BC? I understand that AB is consistently testing bullets and updating values but this seems like a large drop.

Hornady Advertised BC Values:
G7 = .326
G1 = .626

Applied Ballistics old BC Values:
G7 = .322
G1 = .629

Current Applied Ballistic Values:
G7 = .301
G1 = .587

 

[284winner]

.326/.646 is what Hornady has for that bullets BC value. I think it actually falls about .6 or just above. My experience at the range says just above .6 but I'm not Brian Litz and do not have the ballistic equipment used to verify true BCs. It's only my drop data based on velocities and environment.

 

[STOMP442]

Like I was saying, if I plug in the .322 G7 value my observed drops and calculated drops with the app are running within one click on the scope. If I use the current G7 value of .301 in the app I am having to dial a full minute more than the app calls for past 700 yards. The older value is giving me a better solution and normally Brians data is spot on for me.

 

[284winner]

Like I was saying, if I plug in the .322 G7 value my observed drops and calculated drops with the app are running within one click on the scope. If I use the current G7 value of .301 in the app I am having to dial a full minute more than the app calls for past 700 yards. The older value is giving me a better solution and normally Brians data is spot on for me.

Yes. I have both the older Amax and some newer ELDs and my drop data is almost identical in both. Again this is in my rifles in .260 and 6.5-284. I believe Hornadys numbers to be high and Brian's to be low. Somewhere in the middle is where I think you'll find the correction.

 

[JaoeyP]

I've only shot it past 600 once, but using Strelok Pro, updating weather conditions/atmospherics, I was within .1 mil of the solution in the app using Hornadys G7 BC from 800 to 1200 yards. These were a newer lot (2018 MFR).

 

[Jarhead6870]

The bullet never lies.

Ballistic programs provide elevation drops based on formulas and other information you provide to give you “theoretical” numbers at a specific distance. While atmospherics are a factor, two numbers that have significant impact on your elevation drops at that distance are muzzle velocity AND bullet BC. Many people use the velocity calibration feature to true their “theoretical” numbers to their “actual” elevation drops based on shooting in field conditions to allow the program to align better across the board with their gathered DOPE.

This said, why calibrate a muzzle velocity that was obtained at the muzzle and known to be true? Based on this logic, many shooters I know (myself included), change the BC to align the program to match actual elevations. Personally, I use the velocity calibration at shorter distances for very minor truing (less than 10 fps) and change BC for truing at longer distances.

 

[Rob01]

Hornady lists their BCs for the ELDs here. https://www.hornady.com/support/ballistic-coefficient

Confussion came when they were initially sent out with 800 yard averages which was the .626 number and then they changed them to the 200 yard averages of .646 to give the shooters a better side by side comparison to other bullets as most all are 200 yard averages.

As to the BC at longer ranges, I started using the Hornady 4Dof program when it came out last year and found it very accurate to over 1250yards. Hornady uses doppler radar to get and use the banded BCs in their program. Even Litz says doppler is the best way to get BCs. If you needed a single number to put into another program for out to 1000+ shooting then take the three banded BCs above and average them and use that number. It will come in close. I can tell you that current AB number is way off and I am not even sure how they got something that low for the 140 ELD.

 

[STOMP442]

I am hoping this is a simple typo or some other mistake someone made in the latest AB App update or something. I know how to get better solutions and find better information I am just interested in an explanation as to why the data for this bullet has changed so much. I guess this a question for Bryan or one of the guys over at AB. I was just wondering if someone on here knew something I didn't as to what was going on.

 

[Rob01]

Can't speak for anything AB related but there was confusion with the 800 yard vs 200 yard when the BC on the box was changed a while back. There was no bullet change. Just the average.

 

[Edwin Gideons]

I've come to the conclusion that any bullet not a Berger doesn't get much attention in the AB suite of tools. I have trued my BC for the 140 ELD-Ms in my 260AI to .317, verified out to 1200. If I shoot any further than that I switch from Strelok Pro to the Hornady 4Dof.