Range Report Frustrating Ballistics Solution Problem

[gilk]

I'm shooting the new hornady 147gr ELDM in my rifle and the first time I shot the load I was consistently low 0.5mil at 4-600 yds from what my ballistics calculators told me. I've verified my zero, calibrated my scope turret correction factor (SWFA SS 3-15 FFP), chronographed my loads at 2758fps (V3 magneto speed), and meticulously verified all of my inputs. I'm doing the same thing I do for every one of my guns and I haven't had this problem. At such a short range, I can't think of anything that would cause that kind of error.

I thought maybe the difference was shooting prone in grass to zero and concrete to shoot. I verified that this has no affect on poi. The gun shoots 1/2-3/4moa and the 0.5mil error is repeatable and consistent. The scope tracks well and returned to zero after calibration to 14mils.

4 separate ballistics programs agree the solution is 3.6mils at 610 yards but I had to dial 4.1 to hit the target; I needed 2.5mils at 423 yards when the computer says 2.0.

What am I doing wrong?

 

[newguy2k3v2]

Give us all the inputs you are putting in. MV, Density altitude or pressure and temp, sight height, BC, G1 or G7, all of it.

I just used the listed bc in ballistic ae, and somewhat generic on the other inputs besides your MV and came out with way different.

 

[gilk]

0.351 G7 BC
2758 fps
1.91" scope height
100yd zero

I didn't populate any of the atmospheric data, the zero and shooting day conditions were very similar tho and any small errors due to pressure or temp wouldn't add up to 0.5mils. I believe it was 85 deg and 30.08 inHG

 

[gilk]

I've used Ballistic, JBMBallistics, Bullet Flight, Applied ballistics, and Sterlok.. all at 3.6-3.7mils....Its acting like an input error but I have no idea what it could be.

 

[_Windrider_]

0.351 G7 BC
2758 fps
1.91" scope height
100yd zero

I didn't populate any of the atmospheric data, the zero and shooting day conditions were very similar tho and any small errors due to pressure or temp wouldn't add up to 0.5mils. I believe it was 85 deg and 30.08 inHG

30.08 inHg? You are using corrected pressure not absolute pressure.

Where re are you getting your environmental data from?

what is the elevation where you are shooting? What calculator are you using?

 

[newguy2k3v2]

You're positive your zero is right? I had a similar head scratcher but I was hitting .3 high and it turned out my zero was off by that. I don't know how it happened but it did.

There wasn't a heavy still mirage when you were zero'd was there? It can cause the target to look higher than it actually is sometimes. I've noticed it at longer distances.

 

[gilk]

I was using the Applied ballistics app automatic weather feature (I know thats not perfect but my kestrel batteries were dead and it didn't change the solution from standard atmosphere anyway).

Elevation was around 600ft.

I confirmed my zero before I went to the range and when I came home I reconfirmed (windage was off maybe 0.2 but elevation was still good). I zeroed it again and ran the scope up 14mils at 100yds to calibrate my click value and came up with only 1% average error over 14mils (in the opposite direction of my 0.5mil mystery error). I reconfirmed the zero again after the test and it held.

I don't recall much of a mirage during zero but it was hot in the middle of the day.

 

[_Windrider_]

I was using the Applied ballistics app automatic weather feature (I know thats not perfect but my kestrel batteries were dead and it didn't change the solution from standard atmosphere anyway).

Elevation was around 600ft.

I confirmed my zero before I went to the range and when I came home I reconfirmed (windage was off maybe 0.2 but elevation was still good). I zeroed it again and ran the scope up 14mils at 100yds to calibrate my click value and came up with only 1% average error over 14mils (in the opposite direction of my 0.5mil mystery error). I reconfirmed the zero again after the test and it held.

I don't recall much of a mirage during zero but it was hot in the middle of the day.

change the atmospherics. make sure in the settings you have pressure is absolute on. use 29.32 and 85 degrees and see what the solution says. also, when you got that MV, was it that day or another day at a different temp? AB requires 1 of 2 things, either a calculated change in fps per degree or you can plot a table with different velocities at different temps and it does it for you,

My guess is 1 of 2 things. Either your MV is wrong and/or the pressure was making it think it was at a different DA than what you really were.

 

[gilk]

[No message]

 

[samb300]

Did you shoot any other guns with known DOPE next to it during the same range session?

At a match last month, mid-day, the mirage was making everyone pull their hair out. At 400 yards I had to hold ~0.3mils UP to impact, and at 600 yards I was holding over almost 0.5mils. Just a thought.

 

[gilk]

I didn't shoot any of my other guns but there was a shooter next to me shooting the same bullet and he didn't have any problems out of either of his rifles. he said he calibrated the BC to 0.351 which is what hornady advertises so I assume he wasn't having the same issue.

 

[_Windrider_]

What about my question regarding the MV? Was it measured that day or a different day at a different temp?

i use AB as well, going to try and recreate everything you did in mine and see what it says so if I could have your zero info when u get a chance. I have very good success with AB so I'm curious.

 

[gilk]

[No message]

 

[_Windrider_]

I need your zero atmosphere (pressure, temp and MV at the time you zeroed) and i am also assuming 1:8 twist in 6.5 creed?

 

[gilk]

[No message]

 

[_Windrider_]

Well I got the exact same thing as you when I made my zero atmosphere the same as what you said you were shooting in. I think you need to start from scratch.

rezero and record your actual zero atmospherics and save them in the ammo profile. get a muzzle velocity for this zero temp (don't zero with MS attached, but get the velocity either before or after you zero).

take that MV and your 2758fps at 85 and figure out the difference in fps/degree and be sure that field is plotted in the ammo profile. then when you go out and shoot make sure you use all the correct inputs and see what happens again. im sure its a MV error and since you don't have your exact zero range and atmospherics and MV, the algorithm is no good.

AB doesn't require you to change the BC, the BC isn't your problem. the problem is your MV and the MV Variation.

DocUSMCRetired any thoughts on this?

 

[samb300]

Any chance you transposed numbers in your velocity data from the magnetospeed? If I input 2578fps instead of 2758fps I'm curiously close to your 2.5mils and 4.1mils solutions for your given distances.

I just don't see how any 6.5 projectile going 2750fps would need 4.1 mils to 600 yards. I don't think this is a ballistic calculator issue.

 

[gilk]

[No message]

 

[gilk]

[No message]

 

[samb300]

Fair enough.

This is what I would do (disclaimer: I'm no expert and I still don't think it's a ballistic calculator issue)

- Head back to the range, early, to beat any heat/mirage/wind.

- Confirm zero at 100

- Adjust scope up in 1mil increments and shoot 1-2 shots until you get to 5 mils. Then go back down and repeat until you're back at zero.

- Measure velocity with magnetospeed (I'm assuming your zero and subsequent shooting were with the MS off the barrel, most barrels have some POI shift with the MS attached)

- Go shoot at your 400 and 600 yard targets and see if you're still low by 0.5 mils. Unless your height over bore is basically 0", your MV is 2500fps, your bullet BC is sub-0.3, or your DA is -4000', there's no way you need 4.1mils to get to 600.

I still think it was a mirage issue, or it's a scope issue that you're not seeing at the max end of your tracking test.

 

[Greg Langelius *]

When my ballistic solutions don't jibe with the POI's, I recheck three things; scope height, altitude, and target distances.

Then, I never accept ballistic computation as the be-all, end-all prognosticator of impacts. As long as it gets me on paper, I consider it to have done its job.

Nothing in shooting is as absolute as we'd like it to be; and when I miss, it's pretty much always me that's doing the missing. But I'm also not consistent enough that my error causes a trending POI deviation.

I verify target distances with the LRF. I don't mess with air densities or barometics, I just get a pretty good estimate of geographical altitude. Then I take my known POI plots and finagle the scope height value within the program data inputs until the POI's and predictions fall as close into line as I can get them. Any remaining 'error' I just accept.

Air densities, up/downdrafts, and winds are not constant along the entire trajectory. Those density variations are a big part of what creates mirage.

When predictions and POI differences take a new trend at a particular distance, it often correlates to a terrain feature that modifies the motions of the intervening air mass. Where does the cue ball go after it grazes an object ball? Even a light graze produces a trending deviation.

The problem with ballistic programs is that they assume a lot of variables will always remain constant. In a real world, they don't. At their very best the programs are only a generic solution to a set of very complex and dynamic variables.

As a former IT programing professional, I'll tell you that you can write a program to predict just about anything, but also that once you start getting more and more specific, two other things also happen. First, as you try to enter all those additional variables, some of the ones you've already entered have already changed before you can execute the program. The second thing is that some of those variables are not going to get reliably and precisely reported, building in guaranteed inaccuracies.

If we accept programs that are simple enough to be relatively timely and reliable, we also have to accept that the resolution of the solutions will need to be relatively vague. It's a necessary and practical trade-off.

Greg

 

[Long Range 338]

4 separate ballistics programs agree the solution is 3.6mils at 610 yards but I had to dial 4.1 to hit the target; I needed 2.5mils at 423 yards when the computer says 2.0.

What am I doing wrong?

I'm not the expert by any means here but it sounds like the key here is 4 separate programs giving you the same data. If they are all giving the same data, they are all receiving the same data from your input. Frank and Doc have some very helpful posts on how to do proper setup here in this section if you do a little searching. Good luck I'm sure you'll get it resolved with the excellent resources available here.

 

[newguy2k3v2]

How did you calibrate your scope to 14 mils? A group at every mil and measured at a known distance?

I remember the Steiner t5xi had that issue with "ghost clicks" or whatever they called them adding .2 for a .1 mil adjustment sometimes.

 

[ubet]

I don't trust muy chrono. I get a zero, input all the atmospheric stuff then start going back and putting groups I paper. From the I just used the true velocity function and as long as it matches what I'm seeing on paper, I'm happy. I just reworked a new load for my 308. I put in the actual dope into applied ballistics, shooter and ballistic arc. Ab is the only one that was true across the whole range for what I saw I real life.

Sent from my SM-N920V using Tapatalk

 

[gilk]

I set up a target at 100 yds (measured with a tape) and zeroed. I dialed up 14 mills and shot another group and measured the actual poi shift vs 14mils. I was only off 0.5" over 51" (1% error). I shoot this test on a plumb line and a bubble level on my scope.

my problem is that I only have a 200yd range at home and nowhere really to shoot on paper past that.

I can't see the scope error being nonlinear but i'll shoot every mil or 2 on paper and see what happens.

 

[newguy2k3v2]

It would be odd but it's about the only thing left I can think of.

 

[SHLowlight]

Your Rifle cannot match your software, you have to match your software to the rifle, that means truing.

The computer assumes a lot, it has not idea about you the shooter, which has a huge influence.

It only knows what you tell it as far as zero range, the true zero range might not be, 100 yards like you think, you can adjust that. Same with the BC, it might not be what is advertised because you are pushing it too slow or spinning it different than they did when they figured it. You can adjust these factors for your system

Depending on the software it will add and subtract things you might not realize, and turning on all the options might be hurting your results

The rifle system, which includes, Rifle, Scope, Shooter, Ammunition is correct, your software is not

 

[gilk]

I shot a scope tracking drill today, see picture below (ignore crap group on 2 mil line). Seems to be tracking correctly but in doing so I noticed something odd. The poi shifted 0.2 down and 0.2 right.

I zeroed the last time I shot and now I'm off the amount I had to shift my zero last time. My loads were made up from a mix of new unfired brass and 2x fired brass. Is it possible that these different loads are causing a diff poi shift?

 

[_Windrider_]

Did you rezero and record your atmospherics?

 

[gilk]

No, I'm going to prep all my brass the same and then rezero and record all my info. Running low on H4350 and I have to save enough for an upcoming match so I'm being very stingy with my shots.

 

[gilk]

Zeroed today and shot a group at 270yds (longest I have) without dialing any correction on my scope. See the pics for the results. With a confirmed zero the solution was 0.9mils and I measured a drop of 0.89mils so it appears my problem is solved, at least to 270yds.

We'll see what happens in my match but I guess the new unsized brass was causing a poi shift?

 

[_Windrider_]

Zeroed today and shot a group at 270yds (longest I have) without dialing any correction on my scope. See the pics for the results. With a confirmed zero the solution was 0.9mils and I measured a drop of 0.89mils so it appears my problem is solved, at least to 270yds.

We'll see what happens in my match but I guess the new unsized brass was causing a poi shift?

So if you update AB with your zero atmosphere and then go to the solution and put in the atmospherics of where you were shooting with the original problem, what does it look like?

 

[gilk]

Exactly the same, 3.6 mils. That atmospherics don't make anymore than 0.1mil difference at that range.

 

[TheGerman]

Had a slightly similar thing come up with a rifle/load in FFS.

Assuming you have a good zero and atmospherics, start reducing your input BC until you hit where your target is at distance with a known 100y zero. Chances are it will be on at longer ranges and you're set. Listed BC from bullet manufacturers is rarely the correct BC.

Also make sure there is absolutely no parallax as well as you are not shooting up or downhill by more than 10 degrees (if you are, a cosign adjustment may be a small part of where you are off)

 

[_Windrider_]

Had a slightly similar thing come up with a rifle/load in FFS.

Assuming you have a good zero and atmospherics, start reducing your input BC until you hit where your target is at distance with a known 100y zero. Chances are it will be on at longer ranges and you're set. Listed BC from bullet manufacturers is rarely the correct BC.

Also make sure there is absolutely no parallax as well as you are not shooting up or downhill by more than 10 degrees (if you are, a cosign adjustment may be a small part of where you are off)

The published BC is only valid at the given MV since velocity is a factor in the drag coefficient which is a factor in the coefficient of form. So unless your MV is exactly what is advertised on the box, the BC isn't 100%

 

[brettb614]

Look up @lowlight's "Weaponized math" and use it to construct your DOPE, then true your computer to that data by adjusting BC, mv, etc. These computer programs can't get every parameter to match what your load is doing, so you have to tell it once you have good repeatable data. I've enjoyed following this thread. Lots of interesting reading.
I would also recommend taking Frank & Marks Precision rifle course. I just did and was blown away with how simple and effective their methods are

 

[Lowlight]

1. You have to true the data, you cannot match the rifle to the computer, you must match the computer to the rifle, so if you did not establish your correct DOPE how do you expect the computer to be correct

The fallacy is, you can chronograph a load, insert the published variables, and you will have a corrected solution, never happens like that. Plus a computer cannot manage your marksmanship.

2. Weaponized Math is one variable, gravity, it works on all objects the same, so using weaponized math first solves the problem of truing a computer

You start at 300 yards, you get point of aim, point of impact for that yardline then you multiple that number (mils or Moa) by 1.75, this answer will give you the correction for 400 yards. Because of the variables out there, weather, shooter, scopes, etc, you may need to change it a .1 or .2 to hit Point of Aim / Point of Impact.

With your 400 data in hand you multiple it by 1.45 that solution will give you the 500

Once you actually DOPED the rifle, you can then take the information and align your software... Fuck MV just use a place holder because the software will change it anyway, I use 2650 for 308, 2750 for 6.5, 2850 for most other stuff like magnums or 6mm. Fill out your profile as needed, then with a clean profile (data is worthless still) you can TRUE the computer using your Weaponized Math data.

You first adjust the range to 600 yards, you need to use your Place Holder MV to adjust +/- 25fps per .1 Mils until the 600 yard number matches your weaponized math data. Doesn't matter how much you move it, just move it until It matches. Then change the range to 800 yards.

Now at 800 yards if the numbers are not the same, move your BC number up or down to match the 800 yard data. I use the middle number first.

You can fine tune by repeating that at 1000, but it should be good. Anything off by .3 can be ignored. Chalk it up to a bad yard line or poor shooting. The computer will be right at that point.

Weaponized Math is so fucking good, a guy got the X-Factor Numbers tattooed ...

This will dope everything that is zeroed at 100 and shoots to distance, so 223 to .50... it's gravity.

March out and enjoy with none of the headaches

 

[Conaso]

Look up @lowlight's "Weaponized math" and use it to construct your DOPE, then true your computer to that data by adjusting BC, mv, etc. These computer programs can't get every parameter to match what your load is doing, so you have to tell it once you have good repeatable data. I've enjoyed following this thread. Lots of interesting reading.
I would also recommend taking Frank & Marks Precision rifle course. I just did and was blown away with how simple and effective their methods are

 

[BravoXray]

Yeah I have to chime in after taking the class last week and putting it into use. Put down the App and pick up a pen. The weaponized math works. After you get your dope put that into your app.
Friends don't let friends chase dope. Tattooing is optional.