trajectory help please...

[grit]

Did some shooting today. I recorded my poi's, to build a data card. I've played with a couple ballistics calculators, and can't quite tweak them to get the same results.

Rifle: Winchester 70 24" sporter
caliber: 270 win
load: 140 grain sst bc-.495
RL19 56.4
federal 210
remington brass
Mv: unknown

Come ups required for poa impact:
500 yards- 8 moa
600-10.75 moa
700- 14.25 moa
800- 18 moa

Temp: 55 degrees
Elevation: 4000
Cant: 5 degrees

Can someone help me build a card from this info? Why can't I get a match?

[Tim Behle]

I'm in the same boat as you. It would be nice if someone would come up with a ballistics program that would allow you to put in actual drops and bullet speeds for each shot, then adjust bullet's BC and create a working drop chart.

One load I worked up a few days ago, the Point Blank program said that I'd need 16 3/4 MOA to be on target at 800 yards. Turned out I only needed to come up 12 MOA. But it won't let me Input the actual numbers.

Sometimes I think these Ballistic programs are designed by Dan Lilja. Because by the time I get a barrel figured out, it's shot out and needs to be replaced!

[CAM]

grit

I don't shot a 270 so I could be way off base here.
with the info you gave, the key is 10MOA between 500 and 800

Try 2935 Fps with a 150 yard zero

CAM

[edge]

What is the height of the sight above the muzzle?

Are you Zero MOA @ 100 yards?

Best guess as to MV?

Adjusted B.C.( 0.570 ) or Sea Level B.C. (0.405 )??

edge.

[royinidaho]

You entered the realm where I once was. The problem is that I'm still there [img]/ubbthreads/images/graemlins/grin.gif[/img]

Gotta run to work at the moment, will respond later today if some one else doesn't nail it.

If you have some time and have microsoft excell build a table of you data and graph it. Then generate the equation for the curve. Do whatever gets the best fit. R = 1 for perfect.

If all of this is jibberish, I'll do one for you and send it.

You don't have to worry about the unknown velocity. Just so the drop chart works.

Heck, all you wanna hear is "bonk" [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]

[edge]

[ QUOTE ]
SNIP

You don't have to worry about the unknown velocity. Just so the drop chart works.

Heck, all you wanna hear is "bonk" [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]

[/ QUOTE ]

For your needs Roy in Idaho is right.

If you want to use a program then you either need more info or just play with the numbers.

I would like a few of the closer drops for back testing your curve.

edge.

[Dave King]

This is close although it may be of no value. You'd need to check your 100 yard zero and some of the other intermediate ranges.



Velocity (fps)......3060
Bullet Weight (gr)..140
Bullet BC..............0.430
Start Distance......0
Range Increment...25
Altitude (ft)........4000
Temperature (F)....55
Scope Height (inch).1.75
Mil Value (3.44, 3.6).....3.440
MOA value (1.0, 1.047)..1.047
Zero Range (yds)........100


<font class="small">Code:</font><hr /><pre>
Range Vely Energy Total Bullet MOA Mil
yds fps ft/lbs Drop Path Drop Drop
0 3060 2910 0.0 -1.8 0.0 0.00
25 3010 2816 -0.1 -0.9 -3.6 1.05
50 2961 2725 -0.5 -0.4 -0.7 0.21
75 2912 2635 -1.1 -0.1 -0.1 0.02
100 2864 2549 -1.9 0.0 0.0 0.00
125 2817 2466 -3.1 -0.2 -0.1 0.04
150 2770 2385 -4.5 -0.7 -0.4 0.12
175 2723 2304 -6.2 -1.5 -0.8 0.23
200 2677 2227 -8.2 -2.5 -1.2 0.35
225 2632 2153 -10.4 -3.9 -1.6 0.48
250 2587 2080 -13.0 -5.5 -2.1 0.61
275 2542 2008 -16.0 -7.5 -2.6 0.76
300 2498 1939 -19.2 -9.8 -3.1 0.91
325 2454 1871 -22.8 -12.5 -3.7 1.07
350 2411 1806 -26.7 -15.5 -4.2 1.23
375 2368 1742 -31.0 -18.9 -4.8 1.40
400 2326 1681 -35.7 -22.7 -5.4 1.58
425 2284 1621 -40.9 -26.9 -6.1 1.76
450 2242 1562 -46.5 -31.6 -6.7 1.95
475 2201 1505 -52.5 -36.7 -7.4 2.15
500 2161 1451 -58.8 -42.1 -8.0 2.34
525 2120 1397 -65.9 -48.2 -8.8 2.55
550 2080 1344 -73.2 -54.7 -9.5 2.76
575 2041 1294 -81.0 -61.5 -10.2 2.97
600 2002 1245 -89.2 -68.8 -11.0 3.18
625 1963 1197 -98.1 -76.7 -11.7 3.41
650 1925 1151 -107.5 -85.2 -12.5 3.64
675 1887 1106 -117.5 -94.4 -13.4 3.88
700 1850 1063 -128.2 -104.1 -14.2 4.13
725 1813 1021 -139.8 -114.7 -15.1 4.39
750 1777 981 -151.9 -126.0 -16.0 4.66
775 1742 943 -164.7 -137.8 -17.0 4.94
800 1707 905 -178.3 -150.5 -18.0 5.22
825 1673 870 -192.5 -163.8 -19.0 5.51
850 1639 835 -207.7 -178.1 -20.0 5.82
875 1606 801 -223.4 -192.9 -21.1 6.12
900 1573 769 -240.1 -208.6 -22.1 6.44
925 1540 737 -257.9 -225.4 -23.3 6.77
950 1508 706 -276.1 -242.7 -24.4 7.09
975 1477 678 -294.7 -260.4 -25.5 7.42
1000 1448 651 -315.5 -280.3 -26.8 7.78

</pre><hr />