BC on No-Excuse .504 460

[sdporter]

I have a friend who is trying to set up
a a Vari-x 5 on his S91 .504.
He is shooting 90 grains Pyro Select RS.
Zeroed at 100 yards and 23.75 low at 200 yards. MV at about 10’ from muzzle is 1257 (12 FPS ES) 300 yards, 97” low.
I’ve tried plugging those numbers into a b.c. Calculator and can’t get them to jive.
What am I doing wrong??? I was using Berger’s BC calculator. and everything I tried, came out to only about 80” low at 300 yards with the 23.75 at 200.
He’s trying to have turrets made and I’m at a loss on the BC.
I’ve tried from .22 to .19 (as low as Berger’s program would let me go) and am at a loss……

 

[snapbang]

ShootersCalculator.com | Ballistic Trajectory Calculator

Try this one. You can enter lower BCs than .19

 

[sdporter]

ShootersCalculator.com | Ballistic Trajectory Calculator

Try this one. You can enter lower BCs than .19

Thanks! That got me what I needed at 300 but it’s off 4” at 200???

 

[snapbang]

Then your BC, velocity, temperature, humidity, elevation or all of the above may needs adjusting. As someone stated the BC is different at different velocities. You could be running into that. Anyway, glad it helped.

 

[snapbang]

I have some no excuses .503 420 grains. What BC did you us? I was using .15 in my calculations.

 

[sdporter]

I have some no excuses .503 420 grains. What BC did you us? I was using .15 in my calculations.

I used .16

 

[edmehlig]

How do you determine the BC on a bullet!

 

[Bad Karma]

How do you determine the BC on a bullet!

Magic?

 

[edmehlig]

Magic?

If it's via magic or mathematical, then I'm screwed!

 

[Bad Karma]

If it's via magic or mathematical, then I'm screwed!

 

[sabotloader]

This might help

Jun 28, 2006

Today I picked four represenative conicals to calculate the BC. The BC is the average of three shots fired thru two ProChrono chronographs simultaneously that were 100yds apart for each bullet. All calculations were done with Load from a Disk Version 4.0. The charge was always 80gr fffg Triple Se7en used in each of two White Rifles 97s.

.451s
Bullshop 420gr- 0.268
No Excuses 495gr- 0.326

.504s
Bobs NEW 496gr- 0.241
No Excuses 460gr- 0.202

These BCs are dedicated to Underclocked! 8)

Chuck
NRA Endowment Member