JBM ballistics drop table ???

[Straight Shooter]

59 degrees was about the exact temperature I was shooting at.

 

[dfanonymous]

That's funny right there!
Where did you get that notion?

BC is tied to drag, which changes every single inch of bullet travel (not just one region near Mach1).
Now BC itself can be stable throughout, but ONLY if your drag table is custom correct for the bullet.
Maybe 1 in 250,000 shooters have actually tested, created, and built special software to use a custom drag curve.

OP, have you accounted for higher temperatures than the bullet's BC is based on. Most bullet BCs are based on an atmospheric standard like ICAO, Std Metro, or Std. Army. All three at 59degF

From the notion that I don't have these problems. Ever. From any software that trues, trues on mv. From any shooting using standard drag models, using multiple drags for different distances. But not at 300y specifically.

So the notion is, if you're taking a BC from a semi reliable source, won't be messing with it till transonic. The amount of error it induces from, say the box, to what it truly is has minimal effect on the solution until you get into subsonic ranges.

 

[dfanonymous]

Also the notion that this is still point blank range for most center fire rifles. If I'm qualifying with say an m4 on LITERALLY any rifle qual, and use a 36y zero, I don't need to adjust any bc or have any ballistic profile to hit something at 300y.

 

[Bravo 4]

Check the exact range to the target, if it is closer to 280 yards than you have your answer.

 

[338 dude]

I don't know how to post pics.

Take a screenshot on your phone hit reply then click on attach files and it will ask you where is the file you search your photos click on the photo you want them done then I'll ask you to full size or thumbnail then hit post reply

 

[Mikecr]

From any software that trues, trues on mv. From any shooting using standard drag models, using multiple drags for different distances.

Lying to software about MV is not 'trueing' anything. It is just forcing a drop match -at ONE distance..

The BC entered needs to be close at least if you're to hit your mark across a gamut of distances.
That is, unless your mark is VERY big (like just hitting steel or something)..

 

[dfanonymous]

Lying to software about MV is not 'trueing' anything. It is just forcing a drop match -at ONE distance..

The BC entered needs to be close at least if you're to hit your mark across a gamut of distances.
That is, unless your mark is VERY big (like just hitting steel or something)..

I'm not disagreeing. I'm not saying that it you can just leave the BC at zero. Or 1.

You are wrong about truing however. You are trueing incorrectly if you are matching to only one distance. This is why it's better to true MV 10% under transonic. Kestrel says so, AB says so, accuracy first says so, litz says so, i say so.

Then worry about your box given BC past that or whatever. The goal is somewhere around mach .9.

However, doing so would sometimes mess up the closer ranges so the idea use to be use the BC for different mach ranges and set up multiple profiles for different distances. I got tired of doing that so I use a custom curve.

But we are talking about 300y. And the OP already had a bc that seemed about what Hornady's was. So, the notion is, BC won't matter until trans to .9 Mach.

 

[Straight Shooter]

Bravo 4, you are right on. I think I need to confirm my exact distance.

 

[Mikecr]

it's better to true MV 10% under transonic. Kestrel says so, AB says so, accuracy first says so, litz says so, i say so.

Wait a minute, Berger says: "it's better to true MV 10% under transonic"?
The only way to measure transonic muzzle velocity is with a transonic load. Perhaps with a cartridge for a suppressed gun. If you meant downrange flight times all the way out through transonic, that sounds like a good thing for Berger to setup & do.

I'll repeat again for everyone else; Do not LIE to your software.
For every input that you actually know, enter the truth.
For good bullet path prediction you need to know bullet BC, the air density standard that BC is based on, your local air density parameters, your muzzle velocity, and your sight parameters.

 

[Hatrick]

Check your elevation. In you picture it looks like 00.
sorry, I see 4000 now.

 

[doubledoc]

Did you correct for altitude, humidity, and temp? I sighted in a rifle in Georgia, and had the same diminished drop you described, shooting to targets at 400 yds in Montana....

 

[Kendoist4162]

FWIW actual elevation can be checked several ways. OnX maps and also the Compass app on my iPhone are what I use. If they are different, I use the avg of the two. Usually not much of delta though in my experience. Again, fwiw only

 

[73driver]

Just ran my drop for 6.5C 140 ELDmatch @ 2800fps with 100y zero and get 11.56 inch drop.

 

[Roninco]

Your listed BC looks like a G1 number. Could you have input it as a G7?