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Help With Ballistics PLEASE!

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Unread 05-14-2011, 07:26 PM
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Join Date: Jan 2010
Posts: 879
Help With Ballistics PLEASE!

Yesterday i tried to do some quick yet extensive shooting at ranges from 100-450 yards just to begin to test this ballistics program i used and i was spot on at 100 with a 1/2" group so we know the rifle can do it. But then i backed up to 200 and which i was almost 1-1/2" low. So i checked the program and it said i shouldn't have been. I backed up too 300 and i wasn't even on paper any more and i couldn't figure out what the hell was going on!. I backed it out too 450 and 1 bullet it the bottom right out of 3. So i moved it back into 200 same thing happened. I moved it out too 300 and added 1 1/2 moa and i was on paper this time and then too 450 and added a few moa and this time i was decent.

I would like some help with a ballistics program you guys are using? Im using 243. win, 80 grain factory loads with BC of 0.365 fired at 3330 FPS.

Im trying to practice out too 600 yards but if i cant get too 300 i dont know what to do.
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Unread 05-14-2011, 07:37 PM
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Join Date: Jun 2007
Location: Burlington WY
Posts: 96
Re: Help With Ballistics PLEASE!

Did you just use the manufacturers numbers on velocity and BC? The program will only be correct if you use the corrected BC for your ammo out of your gun. What you want to do is zero the rifle at 100 or 200 yards which ever is the best for you. If you can reset your turret to zero at that range. Use your ballistic program to get you close at a longer range. The longer the better you can shoot. You can either shoot at the longer range and shoot for center or just shoot a group and measure the distance of the group to center. Some programs like G7's, gseven - Home, you can just input the measurement from center to save you some shooting. This will give you actuall data out of your rifle. Then the program will give you an adjusted BC for your rifle. Use this data to print a drop chart for your rifle and it will be right.
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Unread 05-14-2011, 08:17 PM
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Join Date: Jan 2004
Location: Blackfoot, Idaho
Posts: 8,876
Re: Help With Ballistics PLEASE!

Build youself a target as shown in the first image on this thread Long Range Targets It doesn't need to be that tall but tall enough for you to hit the single target at the top @ 100 yards.

Read the article and shoot at your several distances. At each distance aim at the target at the top.

This will reveal your drops.

Use JBM to figure the BC out to your max distance.

Then dial the turrets for each distance. Make corrections as necessary.

I've been told that doing it this way will result in being off by the cosine of gravity. Thus the dialing and adjusting to check things out.

Hope this helps.

I did this once out to 1200 yds. Took all day and I was one tired little boy. It helped.
I may be the slowest guy on the mountain . . . . but . . . . I'm on the mountain!
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Unread 05-15-2011, 09:51 AM
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Join Date: Oct 2007
Location: Patagonia Mountains, Arizona
Posts: 770
Re: Help With Ballistics PLEASE!

Make sure you have the correct value for the height of the centerline of your scope over the centerline of your rifle bore entered in your ballistics program. Don't guess, measure as precisely as you can. All ballistic programs have an entry for that value.

It will wreck havoc if with all downrange drop calulculations the ballistic program gives if you get it wrong. It causes increasingly greater error as the range increases.

Getting the atmopheric measuremets entered is importat too, but that's not very important at 300 or 600 yards unless the values in th program are way off, such as shooting at high elevations. Of course you need the correct bullet BC and muzzle velociity in the program. No ballitics program is better than the data you give it.

Last edited by LouBoyd; 05-15-2011 at 10:03 AM.
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Unread 05-15-2011, 01:27 PM
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Join Date: Jan 2008
Location: Falls Church, VA
Posts: 3,474
Re: Help With Ballistics PLEASE!

Ran your numbers in Exbal at sea level and 100 yard zero. Here's the data....

Will gladly rerun the chart if you can provide more accurate data such as altitude, temp, pressure, sight height above bore
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Help With Ballistics PLEASE!-243-ballistics.jpg  
I'm not gonna shoot here. I'm gonna shoot waaaaaaaay over there!
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Unread 05-15-2011, 10:43 PM
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Join Date: Nov 2008
Location: SW Montana
Posts: 5,804
Re: Help With Ballistics PLEASE!

Through out what all your data was so we can help better, ballistic programs have a learning curve so just keep hacking away at it!
"Pain is weakness leaving your body"
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Unread 05-16-2011, 06:22 PM
dig dig is offline
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Join Date: Sep 2010
Location: Arizona
Posts: 662
Re: Help With Ballistics PLEASE!

2nd on the scope hight, would not have thought it made that much difference but at 780 out of a 300 Wby I was off by just over a .25 inch and it made 9 inches of adjustment trouble, any body have a best way to measure?
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