308 Balistics Data?

NaOH

NaOH

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I'm not sure if this is the right place but here we go.

I'd like to move out from 200m and I'm looking to see my rise/drop for 300, 400 and 500m.

I can't find my Chrony data :( but I'm shooting a 168 grain Hornady HPBT over 45 grains of Varget.

Can anybody help me save some ammo?

Edit: I think I found my Chrony data. Does 2598 fps sound right?
 
NaOH said:
I'm not sure if this is the right place but here we go.

I'd like to move out from 200m and I'm looking to see my rise/drop for 300, 400 and 500m.

I can't find my Chrony data :( but I'm shooting a 168 grain Hornady HPBT over 45 grains of Varget.

Can anybody help me save some ammo?

Edit: I think I found my Chrony data. Does 2598 fps sound right?
Click to expand...

Hi Sodium Hydroxide,

That velocity seems a little low. From the loading charts (http://data.hodgdon.com/cartridge_load.asp) I would expect high 2600s with that load. Of course there are a lot of variables that could affect muzzle velocity.

As for ballistic info, I like using JBM Ballistics (www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi). You can input a lot of info, or just use the defaults for quick rough estimates. They have a selection of popular bullets on a drop down menu if you don't know your bullets' ballistic coefficient. You can change zero, range increments, temperature, elevation, humidity, pressure, and wind and target speed and angle. They will also calculate maximum point blank range for you, and give energy calculations at various ranges.

Inputing the info you gave, using Hornady 168 HPBT from the chart at 2598ft/s, your drop when zeroed at 200m would be -11.7" (-3.4 MOA) at 300m, -34" (-7.4 MOA) at 400m, and -69.3" (-12.1 MOA) at 500m.
 
Thanks guys.

Not without knowing what height your sights are at, and what your zero is. It affects the geometry quite a bit.
Click to expand...

Zero I understand (100m) but once you know that I don't understand how the height above bore makes any difference? Bullet drop should be the same if my sight is 4cm or 40 cm above bore I would think.
 
NaOH,

The difference between 200 and will remain with an 8.5X11 sheet of paper. I'd suggest you use that method and know for sure!

Sight height is a non-issue when adjusting for drop like that.

regards

1,3,7-trimethyl-1H-purine-2,6(3H,7H)-dione :)
 
NaOH said:
Thanks guys.



Zero I understand (100m) but once you know that I don't understand how the height above bore makes any difference? Bullet drop should be the same if my sight is 4cm or 40 cm above bore I would think.
Click to expand...

http://www.gun-blog.com/2010/04/high-sights-are-good.html
http://4.bp.########.com/_bP_PNTfFn9I/S9D_qqjPl7I/AAAAAAAAAJs/170BNwTC05E/s1600/sightheight.PNG

As you can see, sight height affects every point of the trajectory, except at your zero range.
 
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Here is JBM's data based on 168 with a G7 .222 the G1 is .433 ( G1 not used in calculations) Based on 2,600fps

Calculated Table
Range__Drop____Drop
(m)_____(in)____(MOA)
200____-0.0____-0.0
300____-11.7___-3.4
400____-34.0___-7.4
500____-69.2___-12.1
600____-120.4__-17.5


Good Luck
Trevor
 
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The elevation is one of the biggest most important parts to the comeup equation too... besides BC and Vel. The higher you go the less drag there is. Use a BC pgm off the web, it will get you on paper...
 
I memorized a table for a .308 shooting at (I think... 2900 fps, can't remember it's the standard load I use)... but it is nice and rounded numbers:
100 zero
200 .6 mil
250 1 mil
300 1.5 mil
350 2 mill
400 2.5 mil
450 3.1 mil
500 3.7 mil

It's great because I remember it as (in clicks)
(5 + 1)
10
15
20
25
(30 + 1)
(35 + 2)
 
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