Ballistics chart not correct for me...what am I missing

[barefooter56]

agreed....have done it on other scopes on guns that dont align with dope, but not the most recent one. Crosshairs aligned and level...religious about that.

Really still wonder about high elevation and if bullet drop really follows the same curve as low elevation???

tonysnoo,
Go to our website and run your data at the altitudes you were shooting at if you have them. Altitude does affect bullet performance quite a lot. Bryan Litz's book "Applied Ballistics for long range shooting " 3rd edition has a complete chapter dedicated to ballistic programs that would really help you on this.
Take care,

 

[normmatzen]

I'm surprised that Barefoot56 was the only person mentioning how important altitude is!
At 4000-6000 ft, the air is VERY thin compared to zero! And, it will most likely effect ballistics a little farther out.
Also, I didn't notice whether you quoted the ballistics model you used for input to the program. Using G1 may introduce more errors than G7 as well. G1 uses the ballistics of a flat bottomed bullet which is fine if that is what you are shooting, but if you are using boat tail bullets you may also find an error from that at long range as well.

I monitor Density Altitude before and after I shoot Bench Rest to track actual ballistics as it effects the tune of my rifle at long range. I shoot at an altitude of 174 feet and I have seen Density Altitude vary from an actual -1000 ft to 3000 ft! I change my tuner settings to match. The DA number combines altitude, barometric pressure, humidity as well as temperature with altitude usually significant. This number is used by pilots to indicate how easily their plane will get into the sky and how well it will fly once it does!

 

[tonysnoo]

tonysnoo,
Go to our website and run your data at the altitudes you were shooting at if you have them. Altitude does affect bullet performance quite a lot. Bryan Litz's book "Applied Ballistics for long range shooting " 3rd edition has a complete chapter dedicated to ballistic programs that would really help you on this.
Take care,

I ran the numbers on the web site. They run true with my programs. Good alignment with my numbers except 850....3/4 of a minute high

My next step is to do the long vertical line scope test. Actually Im going to do this test with three different gun scope combos that I run 108s in

I sure appreciate everyones help

 

[barefooter56]

I ran the numbers on the web site. They run true with my programs. Good alignment with my numbers except 850....3/4 of a minute high

My next step is to do the long vertical line scope test. Actually Im going to do this test with three different gun scope combos that I run 108s in

I sure appreciate everyones help

Glad to help! Get Bryan's book. A little "truing" may be in order for your data. Bryan's book goes into this . I dont want to sound like a salesman. But I use Bryan's books as desk references all the time. They usually have the answer when you run into " things that make you go , huh?".
Take care,

 

[Keith Glasscock]

Which direction are you shooting? East per chance?

 

[4xforfun]

I don't think I have ever had a chart that was dead on all the way to 1000 yds. The smallest change or incorrect input can make a big difference out past 500 - 600 yds. Your input isn't necessarily wrong but it may be unknown. You may generalize that the humidity will be 65% and it may end up being 80%. If you input the wrong scope height by .25" or the humidity is off it can have a considerable affect. To me, the only surefire way is to verify my charts in real application.

No it doesn't and no it doesn't!! Change the scope height by 1/4 inch (say from 2.0 to 2.25 inches) with a 200 yard zero and your impact will change by 1/10 MOA...that is .8 inches at 800 yards. Change the humidity buy 30 % and the impact shifts less than 1/10th moa at 800.....in fact, The Sierra I-6 program shows zero shifts.

 

[bobinpa]

No it doesn't and no it doesn't!! Change the scope height by 1/4 inch (say from 2.0 to 2.25 inches) with a 200 yard zero and your impact will change by 1/10 MOA...that is .8 inches at 800 yards. Change the humidity buy 30 % and the impact shifts less than 1/10th moa at 800.....in fact, The Sierra I-6 program shows zero shifts.

If you change the scope height by 1/4" and your zeroed at 100 yds, that is pretty close .25 moa at 100 yds which would compute to ROUGHLY 2" at 800 yards....... Aside from that, I was only stating what I personally do to get my chart to coincide with real life experience. I have never input info into a program and had the gun be dead on out to 1000 yds according to the chart. I always field verify my chart. What was your point?????

 

[4xforfun]

If you change the scope height by 1/4" and your zeroed at 100 yds, that is pretty close .25 moa at 100 yds which would compute to ROUGHLY 2" at 800 yards....... Aside from that, I was only stating what I personally do to get my chart to coincide with real life experience. I have never input info into a program and had the gun be dead on out to 1000 yds according to the chart. I always field verify my chart. What was your point?????

The point is you stated there is a "big difference in impact at 500-600 yards" in your post.

That is false.

How hard is that to understand? What do you need me to clarify? The whole point of this thread has to do with inputs into a program not matching up to actual results. You are promoting the "garbage in-garbage out" theory....which is correct. But....the things you are pointing to as "garbage" is not the culprit.

Also, you never stated in your post that you always field test your results....which, in my opinion, is MANDATORY and is the correct approach. Everyone should do actual field testing and tweak the inputs into your balistic app to match actual results as best you can. With that you are SPOT ON!!!

 

[bobinpa]

The point is you stated there is a "big difference in impact at 500-600 yards" in your post.

That is false.

How hard is that to understand? What do you need me to clarify? The whole point of this thread has to do with inputs into a program not matching up to actual results. You are promoting the "garbage in-garbage out" theory....which is correct. But....the things you are pointing to as "garbage" is not the culprit.

Also, you never stated in your post that you always field test your results....which, in my opinion, is MANDATORY and is the correct approach. Everyone should do actual field testing and tweak the inputs into your balistic app to match actual results as best you can. With that you are SPOT ON!!!

Before you start thinking that you made some profound point, maybe you should have re-read my original post BEFORE you became so critical. 1. I said PAST 500 - 600 yds not AT 500 - 600 yds "can make a big difference out past 500 - 600 yds". 2. I said "the only surefire way is to verify my charts in real application". The easiest thing in the world to be is critical...... I guess that's why so many people do it. Now please go police some other threads for correcting and have a nice day while your at it.

 

[4xforfun]

HMMM...evidently I DID NOT read your post correctly where you said " If you input the wrong scope height by .25" or the humidity is off it can have a considerable affect". Maybe my definition of "considerable affect" and yours are not the same. My bad.

And."past 500-600"..lets use 1200 yards....still 1/10 moa (1.2 inches) for 1/4 inch improper scope height input if you use a 200 yard zero and there is 0 MOA change for humidity....again, according to the I-6 program.

And I assure you, there was nothing "profound" about anything I said...it is common knowledge...to most.

Sorry if I offended you.

Tod

 

[bobinpa]

HMMM...evidently I DID NOT read your post correctly where you said " If you input the wrong scope height by .25" or the humidity is off it can have a considerable affect". Maybe my definition of "considerable affect" and yours are not the same. My bad.

And."past 500-600"..lets use 1200 yards....still 1/10 moa (1.2 inches) for 1/4 inch improper scope height input if you use a 200 yard zero and there is 0 MOA change for humidity....again, according to the I-6 program.

And I assure you, there was nothing "profound" about anything I said...it is common knowledge...to most.

Sorry if I offended you.

Tod

I wasn't offended, how could I be? Our opinions are different, no big deal. I was just trying to help the OP by stating what I do to get me charts to match what my guns do.........and I don't use a 200 yard zero.

 

[Midnightmedic]

You just have identified why people miss their trophy elk or mule deer when they come out west! Zero your gun in at 300+ plus yards at sea level and never re-zero at when at 9000' elevation and wonder why missed high. My home range is at 6100' and if I zero my gun at 1000 yards. Then drive twenty minutes to 11,000' elevation it will not hit the same 12" steel at 1000 yards. Sails right over target!!!

Another example my friend in MN comes out with a 1-14 twist 22-250 and can shoot .25 moa 200 yard groups with 53gr vmax at my 6100' elevation range. Same load shot in MN will key hole at 100 yards; elevation is around 1800' there! Just saying this is my real world experience for what it's worth.

 

[bobinpa]

You just have identified why people miss their trophy elk or mule deer when they come out west! Zero your gun in at 300+ plus yards at sea level and never re-zero at when at 9000' elevation and wonder why missed high. My home range is at 6100' and if I zero my gun at 1000 yards. Then drive twenty minutes to 11,000' elevation it will not hit the same 12" steel at 1000 yards. Sails right over target!!!

Another example my friend in MN comes out with a 1-14 twist 22-250 and can shoot .25 moa 200 yard groups with 53gr vmax at my 6100' elevation range. Same load shot in MN will key hole at 100 yards; elevation is around 1800' there! Just saying this is my real world experience for what it's worth.

Assuming you were referring to my post, what did I identify??????

 

[Midnightmedic]

simply put your calculations were for sea level and you were shooting at elevations upward of 6200' elevation and hitting high. JB ballistics has always worked for me and our close shooting starts at 800 and goes to 2000. Always in put altitude with pressure adjusted. Altitude is vital; that is why it is in every ballistic program and bergers ballistic stabilization program.

 

[fourpower]

I shoot a couple of different calibers in steel matches. Both are 6mm. The 108 Berger works the best for me.

I use a magnetospeed and have worked the dope backwards too. I like to use the uncorrected pressure with 0 for altitude for our calculations. We shoot at altitudes of 4200 to 6200. We seem to range from 24.6 to 25.8 in station pressure. We have used multiple range finders to verify the distances we shoot at. There is some slope involved that is not factored in but pretty slight.

Both calibers (6SLR@3090 and 6Fat Rat@2860) seem to follow the dope up to 550 pretty spot on, but at 850 the actual is about a minute less than the dope says to be at. My buddy has the same problem with his dope and 108s.

We have worked the dope back and forward. If we change temps, BC, pressure, etc to get the 850 correct the dope is off for our closer ranges.

Each rifle has different brands of scopes I have seen this problem with hybrids too but not as bad. I wonder if altitude changes the bullet path and somehow allows it to stay afloat longer???? Am I doing the calcs incorrectly???

The reason I am concerned is that we are starting to play with tacticool matches and I want to have a good feeling that my calculated dope with work at any of the longer distances....right now it doesn't.

Ideas anyone?

altitude and temp all make a differents. the higher you go and the hotter it is make a big change! we have never found a program that the bergers fit at long range. we have to shoot and make the changes. we were shooting berger 105vlds and went to 105 hybreds with everything else the same and past 600yds they shot 100yds higher. the 105vld shot into moa @ 900yds the hybreds shot into less than half moa.

 

[Mozella]

........ snip...........
Ideas anyone?

Yeah. Without trying to duplicate your results I'll say this:

Be sure you're inputting your data correctly. Be certain you understand station pressure, barometric pressure, altitude, density altitude, and temperature. For example, if your program expects you to input barometric pressure and you input station pressure, you will have a significant error, especially if you're shooting in the mountains. In other words, make sure you and your app are speaking exactly the same language. Your altitude is quite far above any ballistic apps default value, so be sure you're giving your app the correct values.

Slope is a factor as well. My app lets me measure it using my smart phone and I do that even for shooting matches at 600 yards. I would think ignoring slope is a bad idea if you're trying to get real world ballistics and your ballistics app to match. You may be shooting up or down 3 or 4 degrees without realizing it because eyeballing slope isn't easy.

As others have pointed out (some of them anyway) slight differences in scope mounting and especially differences in scope brands are likely to make only small differences or no difference at all.

Then there is bullet B.C. VERY few shooters are able to measure BC and we go on what the manufacturer claims. It should come as no surprise that better BC claims can be used as a marketing tool. An actual BC which is different from what is claimed (and input into your ballistics app) is another source of error and may be the most difficult variable to nail down.

Coriolis effect and spin drift can be significant at longer ranges, so be sure you take those into account. The effect can be nearly a foot at 1000 yards.

Bottom line: Make sure you don't ignore any significant variable and be sure you're putting in the correct values for each one of those variables. On top of that realize that you may be dealing with a BC which is less than perfect, perhaps because of an aggressive marketing department.

Good luck.

 

[jcampbellsmith]

Tony

What about the terrain you are shooting over? It's unlikely to be flat and featureless out to 800yds. I've certainly been deceived by the terrain at much shorter ranges giving me a shift in vertical from where I expect it to be.

Regards

JCS

 

[davidd]

I shoot a couple of different calibers in steel matches. Both are 6mm. The 108 Berger works the best for me.

I use a magnetospeed and have worked the dope backwards too. I like to use the uncorrected pressure with 0 for altitude for our calculations. We shoot at altitudes of 4200 to 6200. We seem to range from 24.6 to 25.8 in station pressure. We have used multiple range finders to verify the distances we shoot at. There is some slope involved that is not factored in but pretty slight.

Both calibers (6SLR@3090 and 6Fat Rat@2860) seem to follow the dope up to 550 pretty spot on, but at 850 the actual is about a minute less than the dope says to be at. My buddy has the same problem with his dope and 108s.

We have worked the dope back and forward. If we change temps, BC, pressure, etc to get the 850 correct the dope is off for our closer ranges.

Each rifle has different brands of scopes I have seen this problem with hybrids too but not as bad. I wonder if altitude changes the bullet path and somehow allows it to stay afloat longer???? Am I doing the calcs incorrectly???

The reason I am concerned is that we are starting to play with tacticool matches and I want to have a good feeling that my calculated dope with work at any of the longer distances....right now it doesn't.

Ideas anyone?

I have a couple of questions for you.
Have you box tested the scope?
Have you properly calibrated your weather meter for station pressure?
Do you have a good solid 100 yard zero on the rifle?

At 500 yards and under a 6mm bullet going 3100fps DOPE will not change much no matter where you are shooting.
As you have mentioned in your post at 15 degrees and under slope will not be much of a factor .

 

[XBBR Shooter]

tonysnoo,
Go to our website and run your data at the altitudes you were shooting at if you have them. Altitude does affect bullet performance quite a lot. Bryan Litz's book "Applied Ballistics for long range shooting " 3rd edition has a complete chapter dedicated to ballistic programs that would really help you on this.
Take care,

Station pressure is the same as altitude, but more accurate. If you use station pressure, you set altitude at "0". The OP is using station pressure.