Help checking some ballistics numbers

[zigliss]

Folks - just need a bit of help checking my thinking here.

 

I am working up a chart to calculate number of clicks required for a 4-24x50 Ior mounted on a 20MOA rail zeroed at 100 yards reaching out to 1000yards.

 

Here are the important bits:

- Scope clicks - 1/4 MoA

- Rail - 20MOA

- 100 yard zero

 

- 139gr Lapua Scenar - BC 0.615

- Velocity - 2700 fps

 

From a 100 yard zero I calulate, off a 20MOA, rail that I need just over 12Moa (32 without the rail) at 1000 yards or 48 clicks on the turret.

 

Does this sound correct to you?

[1967spud]

can you please tell me what calibre and what height scope is above centre of bore at the reticles please

 

then ill run it through exbal for you, if you want that is

[zigliss]

can you please tell me what calibre and what height scope is above centre of bore at the reticles please

 

then ill run it through exbal for you, if you want that is

 

Cheers Mark:

 

6.5mm and 2 inches.

[eldon]

If your working from a 100 yd zero (reference point) and it takes 12 moa for example to get to x yds then the 20 moa rail makes no difference and is a side issue

 

The calibre if it needs x moa to reach say 1000 yds will still need the same x moa due to the laws of physics.

 

The bit where you say 32 now becomes 12 moa can't be right can it ? Otherwise if you put a 32 moa rail on then the 100 yds and 1000yds zero's would be the same

 

The advantage of the 20 moa rail is that there is more adjustment left in your scope assuming you can get down as far as 100 yds to zero. Therefore enabling the set up to reach further by dialing without using holdover.

 

Basically you are maximising the available scope adjustment.

[zigliss]

If your working from a 100 yd zero (reference point) and it takes 12 moa for example to get to x yds then the 20 moa rail makes no difference and is a side issue

 

The calibre if it needs x moa to reach say 1000 yds will still need the same x moa due to the laws of physics.

 

The bit where you say 32 now becomes 12 moa can't be right can it ? Otherwise if you put a 32 moa rail on then the 100 yds and 1000yds zero's would be the same

 

The advantage of the 20 moa rail is that there is more adjustment left in your scope assuming you can get down as far as 100 yds to zero. Therefore enabling the set up to reach further by dialing without using holdover.

 

Basically you are maximising the available scope adjustment.

 

Thanks Eldon - realised my 'Doh' moment a few mins after I wrote the post. Having zeroed with the rail on it doesn't make any difference.

 

Mark is checking my calcs through Exbal in any case.

[1967spud]

Cheers Mark:

 

6.5mm and 2 inches.

 

6.5 what?

[1967spud]

EXAMPLE 308 Win : Lapua Bullets 0.264" 139gr Scenar

 

 

 

 

 

 

 

 

 

SIGHT IN FIELD

 

 

 

 

 

 

 

 

 

DATA DATA

 

POINT BLANK RANGE DATA

 

 

 

MUZZLE VELOCITY (fps)

2700 2700 TARGET SIGHT-IN HIGH LOW

 

 

BULLET WEIGHT (grains)

139

HEIGHT DISTANCE POINT POINT

 

 

SIGHT HT ABOVE BORE (in) 2

(in) (yd) (yd) (yd)

 

 

SIGHT IN DISTANCE (yd)

100

2 169 108 193

 

 

ALTITUDE (ft)

0 0 4 209 124 242

 

 

TEMPERATURE (deg F)

59 59 6 241 138 281

 

 

PRESSURE @ SEA LEVEL (in Hg) 29.53 29.53 8 268 151 314

 

 

PRESSURE @ ALTITUDE (in Hg) 29.53 29.53 10 292 162 343

 

 

RELATIVE HUMIDITY (pct)

78 78

 

 

 

 

 

 

WIND VELOCITY (mph)

 

10

 

 

 

 

 

 

WIND ANGLE (deg)

 

90 ( 3.0 O'Clock)

 

 

 

 

 

INCLINE ANGLE (deg)

 

0

 

 

 

 

 

 

MAX APPARENT TRAJECTORY (in)

0

 

 

 

 

 

 

BALLISTIC COEFF

0.615

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sight Adjustments Needed

 

Trajectory Values 1 MPH

 

Drop From Time of

RANGE Elevation Windage Tgt Lead Elevation Wind Drift Tgt Lead Velocity Energy Bore Line Flight

(yd) MOA MOA MOA (in) (in) (in) (fps) (ft-lb) (in) (sec)

0 0.00 0.00 0.00 -2.0 0.0 0.0 2700 2250 0.0 0.0000

25 4.00 0.00 2.00 -1.0 0.0 0.5 2663 2189 -0.1 0.0280

50 0.75 0.25 2.00 -0.4 -0.1 1.0 2627 2129 -0.6 0.0563

75 0.00 0.50 2.00 0.0 -0.3 1.5 2591 2071 -1.4 0.0851

100 0.00 0.50 2.00 0.0 -0.5 2.0 2555 2014 -2.5 0.1142

125 0.25 0.75 2.00 -0.3 -0.9 2.5 2519 1958 -3.9 0.1438

150 0.50 0.75 2.00 -1.0 -1.2 3.1 2484 1904 -5.6 0.1737

175 1.00 1.00 2.00 -2.0 -1.7 3.6 2449 1850 -7.8 0.2041

200 1.50 1.00 2.00 -3.3 -2.2 4.1 2414 1798 -10.2 0.2350

225 2.25 1.25 2.00 -5.1 -2.9 4.7 2379 1747 -13.1 0.2663

250 2.75 1.25 2.00 -7.2 -3.6 5.2 2345 1697 -16.3 0.2980

275 3.25 1.50 2.00 -9.7 -4.3 5.8 2311 1648 -19.9 0.3302

300 4.00 1.75 2.00 -12.6 -5.2 6.4 2277 1600 -24.0 0.3629

325 4.75 1.75 2.00 -16.0 -6.2 7.0 2244 1554 -28.4 0.3961

350 5.50 2.00 2.00 -19.7 -7.2 7.6 2211 1508 -33.3 0.4297

375 6.00 2.00 2.00 -24.0 -8.3 8.2 2178 1464 -38.6 0.4639

400 6.75 2.25 2.00 -28.6 -9.5 8.8 2146 1421 -44.4 0.4986

425 7.50 2.50 2.00 -33.8 -10.8 9.4 2114 1378 -50.7 0.5338

450 8.25 2.50 2.25 -39.4 -12.2 10.0 2082 1337 -57.4 0.5695

475 9.25 2.75 2.25 -45.5 -13.7 10.7 2050 1297 -64.7 0.6058

500 10.00 3.00 2.25 -52.2 -15.3 11.3 2019 1258 -72.4 0.6427

525 10.75 3.00 2.25 -59.4 -17.0 12.0 1988 1219 -80.7 0.6801

550 11.75 3.25 2.25 -67.1 -18.8 12.6 1957 1182 -89.6 0.7181

575 12.50 3.50 2.25 -75.4 -20.7 13.3 1927 1145 -99.0 0.7568

600 13.50 3.50 2.25 -84.3 -22.8 14.0 1896 1110 -109.0 0.7960

625 14.25 3.75 2.25 -93.8 -24.9 14.7 1867 1075 -119.6 0.8358

650 15.25 4.00 2.25 -103.9 -27.1 15.4 1837 1041 -130.8 0.8763

675 16.25 4.25 2.25 -114.6 -29.5 16.2 1808 1008 -142.6 0.9175

700 17.25 4.25 2.25 -126.0 -32.0 16.9 1779 976 -155.2 0.9593

725 18.25 4.50 2.25 -138.1 -34.5 17.6 1750 945 -168.4 1.0018

750 19.25 4.75 2.25 -151.0 -37.3 18.4 1722 915 -182.3 1.0450

775 20.25 5.00 2.25 -164.5 -40.1 19.2 1693 885 -197.0 1.0889

800 21.25 5.25 2.50 -178.8 -43.1 20.0 1666 856 -212.4 1.1336

825 22.50 5.25 2.50 -193.9 -46.2 20.8 1639 828 -228.6 1.1789

850 23.50 5.50 2.50 -209.8 -49.4 21.6 1612 802 -245.6 1.2251

875 24.75 5.75 2.50 -226.5 -52.8 22.4 1586 776 -263.4 1.2720

900 26.00 6.00 2.50 -244.1 -56.3 23.2 1560 751 -282.1 1.3197

925 27.00 6.25 2.50 -262.6 -59.9 24.1 1534 726 -301.7 1.3682

950 28.25 6.50 2.50 -282.0 -63.7 25.0 1509 703 -322.2 1.4175

975 29.50 6.50 2.50 -302.4 -67.6 25.8 1485 680 -343.7 1.4676

1000 31.00 6.75 2.50 -323.7 -71.7 26.7 1461 658 -366.2 1.5185

[1967spud]

this may be better for you

 

[zigliss]

Great - thanks Mark - I had 31.8 MOA throuhg the programme I was using so close enough!

[Guest varmartin]

Her is my take on it ..........

 

All you need to know is ....BC....Velocity ...sight adjustment specs...zero point and scope height......for a drop chart !!

 

It does not matter what calibre, case, bullet weight , bore size, scope base ...........etc etc

 

Then fine tune it with the ` field and range conditions ...ie, temp, alt, relative humidity and pressure ......