Can somebody check my numbers

G

Guest

Guest
What is the drop on your math? I need to fine the discrepancy,I'm getting different numbers or I'm making a mistake elsewhere.I have 18.6 inches of drop.
 

Brent

Well-Known Member
Joined
Jun 12, 2001
Messages
2,537
Location
Palmer, Alaska
Frank,

My programs say 4.4, 4.45 and 4.4 moa.

The two that give drop say 18.47" and 18.65".

Not sure what Darryl used, but it's quite different.

I used Oehlers Ballistic Explorer, Load From a Disk and Horus Vision's ATRAG (SMOA) respectively. All at 35 deg, 300 ft elevation, 3340 fps and .55 BC.

Either your 100 zero is .5 moa high, the BC is actually higher, the velocity is actually higher, a combination of the above three or the G1 drag curve doesn't accuratly model the bullets trajectory exactly.

Shooting at longer range should help to clarify things better.

Good luck.
 
G

Guest

Guest
Brent, Your numbers track exactly with mine. But Daryls track with what I got at the range.
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4mesh063

Well-Known Member
Joined
Dec 8, 2002
Messages
374
Like Brent said, "zero 1/2moa high?"

Are 1/2 of your bullets above the x at 100 and 1/2 below or all above. If your weighted center of your group at 100 is 1/2" high, you are hosed.
 

Brent

Well-Known Member
Joined
Jun 12, 2001
Messages
2,537
Location
Palmer, Alaska
Darryl,

Did you get those numbers from the Oehler program or was that your actual data from something you shoot that was close to his?

I ran the numbers on the Oehler program again and it would have to have a BC of 2.0 at that velocity or a velocity of 3600 fps at the .55 BC for the 3.6 moa to work out at 400 yards.

The other likely possibility is this, the bullet is still traveling in it's upward path as it crosses the 100 yard zero .2 moa low (it's first of two zero points) and hits .2 moa high at 400 yards. The second zero was actually at 140 yards before the scope was dialed up 16 clicks, or 4 moa.

As you know, the bullet crosses the LOS (line of sight) twice and the first time on it's way up, the second on it's way down and this has quite an effect on our close range zero if we're not carefull. This could be a big part of it here. The 100 yard zero, if correct should produce about 2" drop at 200 yards and 8" drop at 300 yards.

Good luck.
 
G

Guest

Guest
Excelent point Brent. I had forgotten about the 2 crossings of the LOS. I'll bet that is the problem.
 
G

Guest

Guest
I was shooting and got zeroed at 100 yards.Shooting a A-max with a published bc of .55. Speed 3340fps. I moved to 400yds and since I didn't have any numbers with me I guessed 16 clicks on my leupold. I got a perfect direct hit.
After cheching my numbers this doesn't make sense. Can somebody else run the numbers for me.Very light wind,35 degrees 300ft elevation. Thanks
 

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