Ballistics calculators don't match real world observation

[rrstein82]

So I'm relatively new to long range shooting. I have a Springfield Waypoint in 6.5 CM, and shooting a hand load - Hornady 143 gr ELD-X with 41.5 grains of H4350 powder. The Hornady manual states muzzle velocity at 2750, and I've chrono'd it with a Magnetospeed v3 at ~2720. When I this load into any ballistic calculator (including my rangefinding binos), they all come out pretty close in terms of come up: ~4.0 MOA at 300 yards and ~6.7 MOA at 400 (just to give a couple examples). Problem is both times I've shot this week, those calculations are significantly off. At 300 yards I was missing a swinging target (12" steel plate) completely. I dropped down to a 3.0 MOA come up and didn't miss. I also got a target out at 300 yards and dialing 3.0 MOA, put 10 rounds in the 9 ring (about 8" in diameter on the target I was using). Tried at 400 and was missing another 12" steel target using the suggested elevation from ballistics software (6.7 MOA). Dropped to 5.5 and was spot on.

I feel like I must be doing something wrong, as I can't imagine every calculator is wrong. Thought that it might be the Magnetospeed and the FPS was way low; when I bump the muzzle velocity to 3000 FPS, the number the calculators give me are almost spot on to the DOPE I established when actually shooting. Any thoughts would be appreciated.

 

[_Windrider_]

Could be many things. First off, what calculator are you using? Things I would check first, make sure the scope height is correct, the BC is correct and and your environmentals are correct

 

[John Glidewell]

You have to true your ballistics app to the gun. First, make sure your inputs are correct, as stated above. Then true velocity at 600ish yards then true BC at distance. I typically use our 1225 target for that. You can also search this site, lots of info on this posted already. I think they even did some video on it.

 

[Lowlight]

1. Dope the Rifle with Weaponized Math FIRST

2. The Computer must be matched to the rifle, the rifle cannot be matched to the computer. That is why we "true" the data to our real-world results, If you have don't have real-world results, get some first. (Hint: Weaponized Math is real-world shooting)

3. Chronographing for ballistic calculators is a complete waste of time. The computer's true by adjusting the muzzle velocity first, so that means any number you chronographed will be changed by default. I just use placeholders and work off the drop and not the chronograph

308 - 2650fps
6.5 - 2750fps
6mm - 2850fps
Magnums - 2850fps

Then understand it is 25fps per .1 mils to adjust in order to match the actual drop recorded. Use 600 yards to set your muzzle velocity and to align it to your recorded drop. So in other words, see what you need to hit the point of aim, point of impact at 600, then adjust the Muzzle Velocity until that number matches.

Computers are not magic, they cannot predict a solution without you telling the computer some basic data about your rifle and no manufacturers I know of, or App Developers have access to your rifle, so you have to put in the effort.

 

[HousePlant]

I got my Savage in a chassis with a Nikon Black scope dialed in with my ballistics app at K&M in Tennessee at their training event. I had to do some funny business with the scope height and a few other oddball settings and then all of a sudden, poof... I was dead nuts every time. Whenever I just use an app without the right environment to validate and refine, I can one shot to about 300 yards... then it falls apart.

Then I went to Cool Acres Sporting Camp for a PRS with the same rifle, same factory Federal Match 168 gr ammunition (but a different lot purchased in 2020), it shot like poop with the K&M Shooting Complex-sourced dope. Either the ammo wasn't made the same as what I used at K&M (which is believable because it wouldn't group at 100 like it normally does with no wind and the same ammo lot was also shooting like poop in my Tikka deer rifle)... or the environment between Cool Acres and K&M is notably different. Or both. Worst PRS match ever.

I then went up to Dead Zero Shooting Park in Tennessee using Hornady American Gunner and, with a click or two adjustment due to the ammo change, the scope and rifle combo was back on target and predictable and shooting bug holes at 100. Something about TN... I should move there.

 

[rrstein82]

Could be many things. First off, what calculator are you using? Things I would check first, make sure the scope height is correct, the BC is correct and and your environmentals are correct

I've tried the Caldwell calculator online, the Hornady app and the Leica hunting app. Scope heigh should be good (used the more exact calculation using radii of the bolt and ocular of the scope.

 

[rrstein82]

1. Dope the Rifle with Weaponized Math FIRST

2. The Computer must be matched to the rifle, the rifle cannot be matched to the computer. That is why we "true" the data to our real-world results, If you have don't have real-world results, get some first. (Hint: Weaponized Math is real-world shooting)

3. Chronographing for ballistic calculators is a complete waste of time. The computer's true by adjusting the muzzle velocity first, so that means any number you chronographed will be changed by default. I just use placeholders and work off the drop and not the chronograph

308 - 2650fps
6.5 - 2750fps
6mm - 2850fps
Magnums - 2850fps

Then understand it is 25fps per .1 mils to adjust in order to match the actual drop recorded. Use 600 yards to set your muzzle velocity and to align it to your recorded drop. So in other words, see what you need to hit the point of aim, point of impact at 600, then adjust the Muzzle Velocity until that number matches.

Computers are not magic, they cannot predict a solution without you telling the computer some basic data about your rifle and no manufacturers I know of, or App Developers have access to your rifle, so you have to put in the effort.

Thanks, much appreciated. Didn't know anything about truing the calculator to the rifle.

 

[_Windrider_]

Thanks, much appreciated. Didn't know anything about truing the calculator to the rifle.

That’s kind of what I was driving too, lowlight just took the shortcut. The important takeaway is the rifle is the truth. The rifle, or bullet, tells the calculator the answer not the other way around

 

[HousePlant]

Strelok Pro is apparently the bees knees.

I use Ballistic: Advanced Edition with good luck.

 

[rrstein82]

Discrepancy makes sense; trying to make the rifle match the calculator rather than matching the calculator to real world data.

With that in mind, does it makes sense that I'd need to increase the velocity in the calculators to 3000 (that's pretty fast for a 143 gr 6.5 I think...). I mean, it seems to work. I shot a lot of rounds confirming at 200, 300 and 400 (1 MOA at 200, 3 MOA at 300 and 5.5 MOA at 400), and to make the calculator match that, I've kept everything the same and increase the velocity to 3000 fps.

 

[_Windrider_]

Discrepancy makes sense; trying to make the rifle match the calculator rather than matching the calculator to real world data.

With that in mind, does it makes sense that I'd need to increase the velocity in the calculators to 3000 (that's pretty fast for a 143 gr 6.5 I think...). I mean, it seems to work. I shot a lot of rounds confirming at 200, 300 and 400 (1 MOA at 200, 3 MOA at 300 and 5.5 MOA at 400), and to make the calculator match that, I've kept everything the same and increase the velocity to 3000 fps.

no thats an increase that is outside of the norm. Thats why i asked about scope height. something is amiss in your setup thats causing that.

 

[John Glidewell]

most calculators have a truing feature. For velocity you would just enter in the actual dope /elevation used and hit calculate or like in a Kestrel it will adjust velocity as you change the elevation. Then you can choose to use that new calculated velocity or not.

It would be helpful to know what calculator you are using and sharing screen shots of your rifle profile inputs.

 

[rrstein82]

most calculators have a truing feature. For velocity you would just enter in the actual dope /elevation used and hit calculate or like in a Kestrel it will adjust velocity as you change the elevation. Then you can choose to use that new calculated velocity or not.

It would be helpful to know what calculator you are using and sharing screen shots of your rifle profile inputs.

Sure. Can upload screenshots in a bit, but I've used the following: Caldwell Ballistic Calculator, Hornady app (4DOF) and the Leica Hunting App.

 

[GrumpyOleFart]

MOA, that's your problem right there.

 

[rrstein82]

MOA, that's your problem right there.

Lol. I have zero understanding of mils...I blame my dad.

 

[Shootnwrench]

I have zero understanding of mils...

If you actually understand MOA you understand MILS.

Triple check and go back through all your inputs. To make sure something isn’t off. Scope height, 100yd zero, etc.

Also, make darn sure the gun isn’t recoiling under you causing the stock to dip and throwing the shot high. Don’t rely on the rear bag to hold the gun up, build your position like your going to shoot without the bag and then bring the bag to the stock to stabilize the wobble.

 

[Holliday]

Lol. I have zero understanding of mils...I blame my dad.

If you actually understand MOA you understand MILS.

Exactly! They are both the same thing, just called out differently. If your turrets match your reticle, you are gtg. Don’t convert between them or to inches etc. and you won’t be confused…….

When using an MOA scope, think in MOA. When using a MIL, think in MIL. Scopes in MOA are generally 1/4 moa clicks. MILs (MRAD) are commonly 1/10 mil clicks.

 

[GrumpyOleFart]

Yup.
Always fun to read the banter between the adherents from both camps.

 

[Long Range 338]

If you’re shooting Hornady bullets 4DOF works well. If you haven’t played with the ballistic apps much you have a learning curve to overcome. Take your time and try to enjoy the process, understanding the main components of your bullets flight path.

I would start by watching Hornady’s videos and walking thru it with your phone in hand step by step.

When you go to the range don’t play with the app, just document your actual results. After you get home, make the app match your real world results.

Follow Lowlight’s advice, he’s been at this a long time and his methods work.

Good luck!

 

[308pirate]

Lol. I have zero understanding of mils...I blame my dad.

If you don't understand milliradians (what mils actually stands for) then you don't understand MOA either.

Instead of getting pissed at me, think about what I said from a fundamental trigonometry point of view.

Then seek more knowledge by reading which will lead to understanding.

 

[rrstein82]

If you don't understand milliradians (what mils actually stands for) then you don't understand MOA either.

Instead of getting pissed at me, think about what I said from a fundamental trigonometry point of view.

Then seek more knowledge by reading which will lead to understanding.

It was self-deprecating comment on my part, not pissed at all. I do understand the trig involved with both MOA and MILs. What I probably should have said is that is that having learned to shoot using MOA, I don't have to stop to think or work out calculations to determine adjustments in MOA, e.g., if I see a round impact 4 inches low at 600 yards, I know I need to dial 2-3 clicks on a 1/4 MOA turret to bring POI up to where I want it. I haven't taken the time (I know I should) to get achieve that level of comfort in MILs.

 

[308pirate]

if I see a round impact 4 inches low at 600 yards, I know I need to dial 2-3 clicks on a 1/4 MOA turret to bring POI up to where I want it.

You're doing it wrong. Converting between linear and angular units is what fudds teach. @Max already advised you to not do so. We do not care about linear measurements on target at all, regardless of which angular system we're using.

Tell me, honestly, how do you measure 4" (with any level of accuracy) from 600 yards away?

What scope is on your Waypoint, BTW?

 

[rrstein82]

You're doing it wrong.

Tell me, honestly, how do you measure 4" (with any level of accuracy) from 600 yards away?

What scope is on your Waypoint, BTW?

Can't without walking out to the target; was just using it as an example. Guess a better example would be at 100, using a target with 1" marks: if POI is 1" low, I would adjust 4 clicks up and POI should be same as POA. If that's not right, then maybe I don't understand it. I'm sure pretty much everyone on this thread is more experienced than me.

Leupold VX-6HD.

 

[308pirate]

Can't without walking out to the target; was just using it as an example. Guess a better example would be at 100, using a target with 1" marks: if POI is 1" low, I would adjust 4 clicks up and POI should be same as POA. If that's not right, then maybe I don't understand it. I'm sure pretty much everyone on this thread is more experienced than me.

Leupold VX-6HD.

Which reticle did you get?

We normally use reticles that have graduated lines in either mils or MOA (and that match the turret adjustment units) and use the reticle to measure the angle between the impact and the point of aim. You can see you missed by 2.5 MOA (making this up) and you either dial 2.5 MOA in that direction or use the reticle to hold off 2.5 MOA from POA in the correct direction to get a hit.

Math is not involved. Ain't nobody got time for that.......

 

[hlee]

Just to reiterate. If you are thinking in “inches at the target,” you do not understand mils or moa, how to use your reticle, or the fundamentals of what the turrets are doing when you make an adjustment to your scope.

 

[Near miss]

Before this becomes mil vs moa thread (we have not had one for a long time, so it is due) I suggest to always check zero every range visit. Until you accustom/grow to the rifle it will probably change with conditions like clothing, lightning, state of mind. And yet more. If your zero is up click or two, it means that your downrange hits also are. You can check the zero after shooting and see if it has returned once you are "warmed up". You want to learn not only your bullets flight but also how you perform.

And try to gather good data. 10 shots per distance is minimum for building a solid dope. Less is viable when time and ammo are scarce but go for quality data and record it. The larger the group, the more error margin is in it to make reliable datapoint down to 1 click. Once you have reliable dope and mentioned experience, routines and habits just 3 or even 1 shot might be enough to confirm it.

If you have no paper targets available I recommend picking a grid memo and marking your aiming point = reticle center there. Then one grid represents 1 click and you mark every observed hit as a circle, then add lines on top of it as more hits stack. But this will greatly improve your spotting and give you STRONG visual indication where the hits are landing on average. It truly is a great tool for me to gather and log data.


And lastly, get a mil scope

 

[VargmatII]

To get the thread back on topic, at least a bit, I have found that if you put good data into a good ballistic calculator, the data you get out is pretty darn reliable.

I use Strelok Pro, and have used it since I got into long range shooting and competition back in 2014.
If you have a good understanding of the rifle spec including scope height and then plug in a BC value and Muzzle velocity value, the data might still need a little bit of truing, but not all too much. You need to stay with known quality components, I normally use Lapua and Hornady bullets and have found their published data to work well.
As a proof for this I can say that my regular range only goes to 300 meters. I can normally only verify what I have at that range, which by many will be percieved as way too short. Then I have to trust that data when I travel to competitions where I have shot all the way out to 1100 meters. Would you believe that I have scored repeatable hits on some pretty small steel plates and paper targets at competitions every year.

I would bet that "rrstein82" has something mixed up in his data or is using bad data in a crap ballistic calculator.

 

[LG65CM]

Double check your scope height input.

 

[Forward543]

Dont ever trust those lying ass bullets. They always give terrible feedback. Always claiming to go where physics told them.

 

[GreenGO Juan]

Be sure you are putting in the correct BC. G1 or G7 that could cause the discrepancy in ballistic calculation you are seeing. G1 .625 and G7 .315 for an eldx. Given that you are using a boat tailed bullet, Id use G7.

As others have said Zero at a set distance and shoot, record your results. Let the rifle cartridge scope combo tell you what it does, that is your true dope. Imo, the ballistic calculatior are tools to get you in the ball park.

Other considerations with the calculators, manufacturers dont rate their bullets the same. Bc changes with velocity. 3-400 yards its not enough to matter, but if you start stretching out further 800 1000 1200 it will.

 

[DownhillFromHere]

Can't without walking out to the target; was just using it as an example. Guess a better example would be at 100, using a target with 1" marks: if POI is 1" low, I would adjust 4 clicks up and POI should be same as POA. If that's not right, then maybe I don't understand it. I'm sure pretty much everyone on this thread is more experienced than me.

Leupold VX-6HD.

OP, look at the example below. Say the two blue dots are impacts. To correct, you would raise elevation 3 and move windage left 1. It does not matter what the range is!!!!!!! Up 3 and left 1. Whether it's 100 yards or 1000, you're moving up 3 and left 1. If the reticle subtensions are in an angular measurement called ghublats, it.does.not.matter. You adjust 3 ghublats up and 1 ghublat left. It doesn't matter if the range is 3.654 phlibbits or 8.1223 phlibbits, you adjust up 3 ghublats and left 1 ghublat.

Linear measurement has no place in making your correction!!!

 

[powdahound76]

Had similar on Tuesday.

Cold and humidity increased my cold bore elevation at 975. From 7.4 to 8.9.
(25F and 77%)

Hit was 1.5 mils high per spotter.

Corrected dope to same as last outing (65 and 22% humidity)
Smack. Smack. Smack.


Had not cleaned, nothing else changed other than atmosphere inputs in Hornady 4dof.
App has been really great across 4 rifles, this outing the exception.

Learning every day

 

[FUNCTIONAL]

I do slightly different and chrono the same day I check dope. When the computer dope is off I adjust BC to get my impacts. After that I plug the different velocity per temp tracking into the kestrel and let it handle the velocity to atmospherics.

Using a kestrel or Shooter app this method has given me the most consistent results through all kinds of weather without having to mess with anything.

If you can confirm everything BUT the BC why would you change your measured knowns to fit something you can't confirm?