Bullet flight path

[Whitetail Hunter]

My local range only has targets out to 300 yards. I have a 100 yd zero and my come up for 300 is about 2.7 MOA. I asked to shoot on a farmers field to 500 yds. My come up and 400 is 6 MOA and 500 yds is 9.6 MOA. The bad part is I don't know my velocity. I am shooting 200 accubonds with 91 gr of H-1000. My book velocity should be close to 3000 fps. According to my actual values to the caculated I am more than a 1 MOA off at 500 yds. Is this typical? [img]images/icons/confused.gif[/img] [img]images/icons/frown.gif[/img]

[Ray Meketa]

Craig

When you say "calculated" I assume you mean one of the ballistic programs. The short answer is, yes, you could be that much off if you don't know the velocity. That's one of the critical numbers in your input data. Ballistic programs are not perfect. If you have actual come-ups you have to trust them and not some program numbers.

[Whitetail Hunter]

cheechako,

I just didn't think that the ballistic programs would be that far off at 500 yds already [img]images/icons/shocked.gif[/img] I gues that my next shooting gadget should be a chronograph.

[Whitetail Hunter]

The caculated velocity was taken from the Nosler manual

[700]

Craig

I assumed the following for your situation.

Min. Possible Velocity : 2700 fps
Max. Possible Velocity : 3300 fps

Min. Possible G1 BC : 0.45
Max. Possible G1 BC : 0.6

Scope Height = 1.5 inches

Standard Athmospheric Conditions

Using some computer code I wrote over the weekend, and a method of least squares, I found that a G1 BC of 0.45 and an MV of 2970 fps suits your drop data quite well.

These values may not even be close to your true BC or Muzzle Velocity but they should produce a pretty decent drop chart from a ballistics program,which will match the data you gave us quite well.


Range Yrds,,Drop In,,Drop MOA
100,0,0
200,-2.70527,-1.29167
300,-10.6921,-3.40342
400,-25.3806,-6.05917
500,-48.6858,-9.29832

Using this
You will be on target at 100 yards.
You will be 0.8 MOA low at 300 yards.
You will be 0.059 MOA low at 400 yards.
You will be 0.3 MOA high at 500 yards.

Hope this helps

Regards

700

[700]

Craig, Cheechako

It is well to remember that ballistics programs can only approximate a bullets flight path.

The G1 ballistic coefficient which most programs use was origionally developed for a particulat projectile. The G1 BC will work great if you you are shooting that particular projectile, but less well, the more different your projectile is from the origional intended projectile.

Rgds

700

[Whitetail Hunter]

700,

thanks for the drop chart. My scope height is 1.8" how did you develop that caculation?