Long range ballistic validation question

[Unastamus635]

Can someone please give me some guidance on this issue:

Gearing up for Wyoming and shooting a Custom .338 Lapua with the 300 grain Berger bullets, H1000 powder, and Lapua brass. Rifle is shooting 600 yards really well at 10.25 MOA. I punched the 600 yard validation data into my G7 rangefinder and also the Berger chart and it said at 1026 yards I should be shooting 28.50 MOA (based on where the rifle was shooting at 600 yards). When we went and shot at 1026 yards the gun was pretty much dead on at 26.25 MOA. Here's what's confusing me. If I punch in the validation data at 1026 yards then it throws me off at 600 yards because the numbers don't match with where the gun is shooting. If I punch in the numbers where the gun is hitting at 600 then its off at a 1000 yards...How do I make them match so I know where to be shooting from 600-1000 yards?!?! Thanks for the help!

 

[Canhunter35]

Have you chronied your mv? If not that's what you need to adjust.
Are you using a g7 ballistic coefficient? Preferably Litz g7 bc.
But your ballistic curve is wrong. I validate by shooting 400 & 500 then move to 450& 550 to ensure everything is working then start walking it out in 100 yd increments, validating your dope. You may also have an environmental set wrong? Make sure you have your density altitude correct if you're shooting to 1k.

 

[Unastamus635]

The range finder is a Gunwerks G7 BR2, it uses the G1 BC. It automatically calculates the barometric pressure, temp, altitude etc. The shots have been chronied but that is not matching up with any of the charts or where the bullets are actually hitting. We shot at 300, 400, 600, and a 1026. Everything was good up to 600, then adding the 1026 into the mix, F'd it all up...

 

[Howland]

My instincts would be to trust the published BC of the projectile and observed ballistic performance over multiple distances over a chronograph readout (or manufacturer advertised muzzle velocity for factory ammo).

 

[Unastamus635]

Agreed!

 

[Barrelnut]

I would eliminate the scope from the equation by doing a tall target test to 10 MOA and then to 28 MOA. Just easy to do and verify.

Things start adding up at 1K. If shooting east or west, coriolis effect could be 4 to 6 inches, which is about 1/2 MOA, I think.

 

[jimbires]

I have the first design G7 rangefinder . on page 29 , setting up a ballistic profile , you can use G1 or G7 . it is called the "DRAG STD " . I use the G7 with my 300gr hunting bullets . I doubt they took this out on the second design rangefinder .

 

[Joefrazell]

Sounds like mv may be slightly off. Also do a tall taget test to be sure your scope is tracking dead on or very close. Most will be off by a small percentage but if its too much it cold show up at longer ranges.

 

[Wedgy]

Use the Litz tested BC, make sure your zero yardage input is correct and the gun is actually on at that range, then adjust the muzzle velocity as needed. Also make sure the unit is at the same temperature as the environment.
Around 11 minutes in they show you how to adjust velocity to the drops

 

[Unastamus635]

Awesome video thanks Wedgy, that helps a ton! I unfortunately did not take the average of all of my shots, and only went with the best one...lesson learned! My only prob now is I don't have access to get back to the 1000 yard range before we leave!

 

[SniperGirl223]

I'm fairly new to shooting long range and am still learning... i was hoping someone could help explain something to me...

I previously ran ballistic charts zeroed at 300 or 700 yards and they would be reasonably accurate as far as I could tell. However, with the longer ranges, beyond 1000 yards especially, the charts have not been as close as they were before. I shoot mostly at longer ranges and rarely go for targets below 600 yards but was finding very different numbers if zeroed at 100, 300, 700 or 1,000. My question is... do you normally get the closest estimate if you use a zero as close as possible to the range you are shooting? How can I get closer quicker?!? What is it that causes such a radical difference in the numbers?

Thanks in advance.

Use the Litz tested BC, make sure your zero yardage input is correct and the gun is actually on at that range, then adjust the muzzle velocity as needed. Also make sure the unit is at the same temperature as the environment.
Around 11 minutes in they show you how to adjust velocity to the drops

 

[Canhunter35]

I'm fairly new to shooting long range and am still learning... i was hoping someone could help explain something to me...

I previously ran ballistic charts zeroed at 300 or 700 yards and they would be reasonably accurate as far as I could tell. However, with the longer ranges, beyond 1000 yards especially, the charts have not been as close as they were before. I shoot mostly at longer ranges and rarely go for targets below 600 yards but was finding very different numbers if zeroed at 100, 300, 700 or 1,000. My question is... do you normally get the closest estimate if you use a zero as close as possible to the range you are shooting? How can I get closer quicker?!? What is it that causes such a radical difference in the numbers?

Thanks in advance.

I need more info, but I would zero your rifle for 100, then you can check your rifles zero with little environmental influence. Then dial to your intended range. Are you using kestrel to input environmental data? Past 500 that starts making a difference. If your density altitude is correct, your gun zeroed, and your dope is still off you may need to tweak your muzzle velocity until the curve matches. As wedgy said use a litz g7 bc. At 1k corealis starts becoming a factor too.

 

[SniperGirl223]

Thanks for your quick response.

I have been shooting a Savage Model 12 LRP in 6.5 Creedmoor out to 1,000-1,400 yards pretty regularly. Dialing to 1,000 yards the first time was pretty close to what I thought... I believe it was the same for 1,200 yards. However, based on the Federal Premium ballistics chart zeroed at 700 yards as a baseline, I thought I would run out of scope adjustment and have to hold over. I was pleasantly surprised the first time and found that I actually had just enough to make it... they were all hitting high using the numbers from the chart. When I ran the chart later zeroed at 1,000, the numbers were much closer. I hope this makes sense...

I do not have any experience with a kestrel and don't know if I have the means to be that precise right now. Direction of fire is approximately NNW with a slight uphill angle.

I'm just now starting to use handloads, but the two main types of ammo I was using before were both factory. Hornady Precision Hunter 143 grain ELD-X at 2700 fps and American Eagle 140 grain OTM at 2700 fps. They have been run through the chrony and tend to run about 15 fps hotter than the box on average.

I have since figured out what I need to do to hit all of these ranges and have done so with success, but I've been trying to backtrack a little and figure out the science behind it and why's as I try for even longer ranges. My current goal is for a hit at a mile+.

Thanks again for your help! I'm pretty new to all of this and am excited to learn more.

 

[Canhunter35]

My best recommendation would be to buy accuracy 1st long range shooting DVD by Todd Hodnett.
But at those distances your current environment data is a must.
For example: I was coyote hunting yesterday morning, when I started my density altitude was around 1500 barely an hour later it was at 2500. I don't have my cards on me, but that translates into an Moa of difference in elevation