Ho do I interpolate on a drop chart?

[17Fireball]

lightbulb
I have shot my gun at 100, 200, 300, 400, and 500. Based on my shooting, I know the "exact/precise" elevation turret settings at these distances. How can I use this actual data to come up with drops at the 25, 50, and 75 yard increments between each verified 100 yard increment; without shooting the incremental distances? Example 225 yards, 375 yards, 450 yards, etc.

Please don't suggest I just chrono the gun velocity and grab the bc and run through ballistic programs to get the drops. This has never worked well for me and I've found actual shooting often gives different dope than the programs.

Here is the information. I would be VERY grateful for the math formula, etc. that I could use for multiple guns to do the same thing by determining the correct dope for the unshot distances based on the precise hard data from my dope shooting the 100 yard distances.

Tikka T3 TCR .260 Rem.

Bullet: Hornady 129 grain InterLock SP

G1 BC = 0.445

Actual Correct Dial Setting for Elevations:

100 Yards = 0
200 Yards = 1.50
300 Yards = 3.75
400 Yards = 7.50
500 Yards = 11.25lightbulb

 

[rcoody]

lightbulb
I have shot my gun at 100, 200, 300, 400, and 500. Based on my shooting, I know the "exact/precise" elevation turret settings at these distances. How can I use this actual data to come up with drops at the 25, 50, and 75 yard increments between each verified 100 yard increment; without shooting the incremental distances? Example 225 yards, 375 yards, 450 yards, etc.

Please don't suggest I just chrono the gun velocity and grab the bc and run through ballistic programs to get the drops. This has never worked well for me and I've found actual shooting often gives different dope than the programs.

Here is the information. I would be VERY grateful for the math formula, etc. that I could use for multiple guns to do the same thing by determining the correct dope for the unshot distances based on the precise hard data from my dope shooting the 100 yard distances.

Tikka T3 TCR .260 Rem.

Bullet: Hornady 129 grain InterLock SP

G1 BC = 0.445

Actual Correct Dial Setting for Elevations:

100 Yards = 0
200 Yards = 1.50
300 Yards = 3.75
400 Yards = 7.50
500 Yards = 11.25lightbulb

What most people do is use your actual drops in a ballistic calculator to create a custom drag curve.

some debate on whether to adjust the bullet BC or the velocity to match you actual drop data.

I am sure many will chime in and say what works for them.

 

[17Fireball]

Thank you for your reply.

I've tinkered around with these programs and despite adjusting velocity to try to match my actual drops, the charts never reflect actual shooting.gun)

 

[cohunter14]

You can use the G7 Ballistics Calculator on this site. Open it up and click on "Trajectory Validation" which is found in the middle of the page. Enter your info and it should spit out an assumed velocity. Hopefully the velocity is fairly close for all five yardages and you can put together the drop chart based on that. If you have some discrepancy in the velocities, put more value into the longer shot velocities than the shorter.

 

[Mikecr]

You declared click numbers instead of IPHY or MOA dialed, which tells me you haven't tested scope adjustments, and don't know the actual amount dialed.
You didn't mention MV, which tells me you don't know it.
You suggested adjustments for elevations, which tells me you didn't measure and enter actual air density parameters.
You implied that ballistic software doesn't work for you, which makes sense to me, given these items and other more difficult potentials.
How good is your ranging?
How accurate is the gun from cold bore shot to shot?

Anyway, no rule of thumb will help.
You might accept your limitations, until reading a book about external ballistics and ballistic software in general.
Then it should be easy to generate a good click card for your true capabilities.

 

[17Fireball]

Just wanted to give a shout out to Bryan Litz who hooked me up with the math to make it work perfectly by using a Linear Interpolation Equation Calculator. Very grateful to Mr. Litz now my brain has peace and I have a solid drop chart. lightbulb

 

[ShtrRdy]

you might try entering your actual data into a spreadsheet and then plot it out. Then you could look at a line fit to the data.

 

[Canadian Bushman]

This

 

[graywolf]

Just wanted to give a shout out to Bryan Litz who hooked me up with the math to make it work perfectly by using a Linear Interpolation Equation Calculator. Very grateful to Mr. Litz now my brain has peace and I have a solid drop chart. lightbulb

If you have collected enough data points, linear interpolation will give you a fit within your data variance but modeling a nonlinear process that way won't work "perfectly" (or even better than a ballistic calculator).