Ballistic apps and potential energy via gravity
- Thread starter Scotchmo
- Start date
When started shooting FT, I went for a while out west without having to shoot an elevated target. I finally went to a match that has a lot of elevated targets and asked a very successful shooter how he dealt with the targets. He told me he used the rifleman's rule which was simply to range the base of the elevated target and use the clicks for the base distance for the elevated shot. So if a target was up in a tree....just range the base of the tree and use that distance the set clicks.
I followed that advice and missed about half of the elevated shots. I don't think the guy that told me the rifleman's rule missed any. That led me to believe that the rule was sound and I just needed practice on the elevated shots.
I dug further into the issue when I got home and realized that the rifleman's rule would actually give me the opposite correction needed on the targets that were shorter than my zero.
After this realization, I made a chart of the proper corrections and never missed another elevated shot after that due to elevation.
The weird part of the whole thing is that the guy that told me about the rule had been employing it for a tremendously long time and his hit percentage was high enough that he never considered that it was telling him the complete wrong direction to correct on his close targets.
For him, in "practical" terms...the rifleman's rule was perfectly adequate despite being completely wrong on the shorter shots.
Over time...it's an absolute certainty that he missed more elevated shots than he should have if he was correcting properly. In Scott's case...this is going to be the same. His small correction will ultimately yield a higher hit percentage regardless of his group size.
Mike
I followed that advice and missed about half of the elevated shots. I don't think the guy that told me the rifleman's rule missed any. That led me to believe that the rule was sound and I just needed practice on the elevated shots.
I dug further into the issue when I got home and realized that the rifleman's rule would actually give me the opposite correction needed on the targets that were shorter than my zero.
After this realization, I made a chart of the proper corrections and never missed another elevated shot after that due to elevation.
The weird part of the whole thing is that the guy that told me about the rule had been employing it for a tremendously long time and his hit percentage was high enough that he never considered that it was telling him the complete wrong direction to correct on his close targets.
For him, in "practical" terms...the rifleman's rule was perfectly adequate despite being completely wrong on the shorter shots.
Over time...it's an absolute certainty that he missed more elevated shots than he should have if he was correcting properly. In Scott's case...this is going to be the same. His small correction will ultimately yield a higher hit percentage regardless of his group size.
Mike
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IMO, nothing is more superior than a very experienced shooter with dope cards made from said experience in a fairly constant environment, however, in real world practices, we face environmental changes from one shooting session to another, to where, either the shooter must have a great sense of these variables and how to adjust to them, or you must rely on some ballistic / trajectory software to make the compensations for you. One rule may apply at distance A for shooter A, but not for distance B, C, or D for shooter B.
The best ballistic software to date takes into account all the factors OP brought to light, and far more. The further your shot from muzzle to target, the more variables you introduce. However, I am unaware of any ballistic software that allows inputs for multiple wind conditions (ie 5mph from 0-30 yards 3'oclock, 4 mph wind 30-60 5'oclock, ect), updrafts...downdrafts, swirls, because that is complicated as heck, and only shooting in the conditions and making adjustments on the fly, hoping those conditions remain, or repeat in the time frame of your next shot, is your only hope.
You may be presented with 5 mph winds that shoot up to 10-15 mph in relatively repeatable intervals over a long period of observation, if you time your shot right, and calculate for the 5 mph winds, you'll likely be on target, however, calculate for 5mph winds and shoot during the 15 mph gust interval, or the interval changes and happens to present itself during your bullets flight, you're gonna miss or be off to a degree, am sure BR competitors know all to well about timing the wind intervals to their best ability.
You ever notice during a walk or hike, without change in elevation, a sudden massive temperature drop, that returns to normal once you exit that location, I'm talking just 5-10 feet of distance, micro-climates exist and can present themselves in your trajectory, including heat, which will effect your point of impact, no matter how small of a degree, due to changes in air density. We don't measure the exact temperature along the entire projectile path for every shot, however in most cases this effect isn't present, but that doesn't mean it doesn't exist nor have any effect when it does.
And when it comes to a shot being off, which variable was it? Wind shift? Temp shift? An imperfect projectile? Change in muzzle velocity? Slope measured or inputted incorrectly? A little from column A and a little from column D?
The list of variables that most ballistic software does not take into account is a lot. Makes me want to go write some formulas into mine, but math is hard.
-Matt
The best ballistic software to date takes into account all the factors OP brought to light, and far more. The further your shot from muzzle to target, the more variables you introduce. However, I am unaware of any ballistic software that allows inputs for multiple wind conditions (ie 5mph from 0-30 yards 3'oclock, 4 mph wind 30-60 5'oclock, ect), updrafts...downdrafts, swirls, because that is complicated as heck, and only shooting in the conditions and making adjustments on the fly, hoping those conditions remain, or repeat in the time frame of your next shot, is your only hope.
You may be presented with 5 mph winds that shoot up to 10-15 mph in relatively repeatable intervals over a long period of observation, if you time your shot right, and calculate for the 5 mph winds, you'll likely be on target, however, calculate for 5mph winds and shoot during the 15 mph gust interval, or the interval changes and happens to present itself during your bullets flight, you're gonna miss or be off to a degree, am sure BR competitors know all to well about timing the wind intervals to their best ability.
You ever notice during a walk or hike, without change in elevation, a sudden massive temperature drop, that returns to normal once you exit that location, I'm talking just 5-10 feet of distance, micro-climates exist and can present themselves in your trajectory, including heat, which will effect your point of impact, no matter how small of a degree, due to changes in air density. We don't measure the exact temperature along the entire projectile path for every shot, however in most cases this effect isn't present, but that doesn't mean it doesn't exist nor have any effect when it does.
And when it comes to a shot being off, which variable was it? Wind shift? Temp shift? An imperfect projectile? Change in muzzle velocity? Slope measured or inputted incorrectly? A little from column A and a little from column D?
The list of variables that most ballistic software does not take into account is a lot. Makes me want to go write some formulas into mine, but math is hard.
-Matt
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Interesting read regarding Mike's remarks on the Rifleman Rule.
en.wikipedia.org
-Matt
Rifleman's rule - Wikipedia
-Matt
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I’m
sin(15 degrees) = 0.259
That is significant.
That angle (15 degrees) and distance (600yds) is what we encountered at 2024 RMAC. The 12” plate only gives a 1moa allowance in vertical or horizontal deviation from the POA.
When extrapolating the .38” at 200yds to get to 600yds, it’s more likely a squared function. So from the .38” at 200yds, I would estimate about 3.4” at 600yds. When trying to hit a 12” plate, a 3.4” error is significant. If the dope had been correct, a 1moa vertical deviation would just clip the edge of the 12” plate. Throw in a 3.4” vertical error and now some of those shots will be off the edge of the 12” plate.
15 degrees has about 26% of the affect when compared to shooting vertically up or down.
sin(15 degrees) = 0.259
That is significant.
That angle (15 degrees) and distance (600yds) is what we encountered at 2024 RMAC. The 12” plate only gives a 1moa allowance in vertical or horizontal deviation from the POA.
When extrapolating the .38” at 200yds to get to 600yds, it’s more likely a squared function. So from the .38” at 200yds, I would estimate about 3.4” at 600yds. When trying to hit a 12” plate, a 3.4” error is significant. If the dope had been correct, a 1moa vertical deviation would just clip the edge of the 12” plate. Throw in a 3.4” vertical error and now some of those shots will be off the edge of the 12” plate.
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That is something different, and it is taken into account by most all ballistic apps.Interesting read regarding Mike's remarks on the Rifleman Rule.
Rifleman's rule - Wikipedia
-Matt
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I was referring to Mike's comments and just adding onto it for anyone interested on that subject matter...I literally stated that in the above reply you quoted...
-Matt
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I did a few shots today up a 7 degree incline and a few down a 16 degree decline. In both cases I used my Labradar but only got decent data out to about 50yds. The thought was that the projectile will lose more velocity when shooting uphill as opposed to down hill. Did not see any pattern of that from the limited data.
50yds is too short for that test. I’ll call that test inconclusive for now. The only way I’ll know if it matters is if my shots average a little low for the far uphill shots. And average high for the far downhill shots.
50yds is too short for that test. I’ll call that test inconclusive for now. The only way I’ll know if it matters is if my shots average a little low for the far uphill shots. And average high for the far downhill shots.
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At 500 yards Hornady app calculates .05 MOA difference, at 50 yards, 0 MOA difference. This is with a 338 cal 185 gr CX bullet at unknown muzzle velocity because I don't see where to input that and am too busy atm to look around and change it.
Obviously your ammo will respond much differently but I think the effect is far too small to be significant under 200yd.
-Matt
Obviously your ammo will respond much differently but I think the effect is far too small to be significant under 200yd.
-Matt
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Ahh found velocity, changed from 2600 down to 1000, now 500 yard = .06 MOA and 50 yard still 0 MOA.
-Matt
-Matt
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Woops, I didn't hit save when I changed velocity..
3 MOA difference going from -15 to 15 at 500yards with 1000 fps 185 gr....so thats what, 15.75" difference predicted by hornady due to inclination change.
-Matt
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That is significant. And it would be even greater for 600yds. And Strelok does not take that into account. Strelok shows -15 and +15 degrees to have the same compensation.
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Yea and the BC on the ammo I used is probably a bit better than what you're using.
600 Yards shows
101.75 MOA vs 96.96 MOA hold overs, so 4.79 MOA...~30"? Lol well that grew a lot from 500!
Also re-checked 50 yards, shows .01 MOA which is what, .005"?
-Matt
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I would not give much regard to the Hornady ballistic app. I had it on my phone before but deleted it. I now installed it again to check.
I used their listing of the .22LR SK Standard Plus, a ammo I use a lot and still have a brick and some more on the shelf. With my rifle zeroed at 50 meter I must dial up 7MOA for 100 meter, exactly what Strelok, Element Ballistics, Chairgun and Mero calculate with the RA4 model, giving me 15mm - 25mm groups at 100 meter with POI = POA. According to Hornady app I must dial up 8MOA.At 200 meter Strelok and others call for 25MOA which is right for my rifle and Hornady ask 30MOA, 5MOA difference at 200 meter with a 50 meter zero.
I checked with my centrefire rifle data as well, but Hornady does not have any of the factory ammo I use in the list. The closest I can find is far off as well. Now I know why I deleted it before.
I cannot find on the Hornady app which BC values they use and also not which drag models they use. And how do you fine tune it? How do you enter custom projectiles in the app? I just don't trust that app for accurate results.
At the end, ballistic calculators are just that, a calculator to bring you in the ballpark if you use the correct data input and drag models. After that it is up to you to do the fine tuning. There is nothing that replace real life DOPE and adjustment according to that.
I still think the hits on that 25" x 23" plate is good. Considering the one rifle shot mostly on the top half and the other on the bottom half of the plate, I think the data was as near as could be without fine tuning. If the error was because of apps not accounting for the down slope shooting and extra velocity, that had an opposite result on one rifle from what would be expected and is discussed. Like Miles aka Ballisticboy say, drag models are a general calculation for a group of projectiles in a general form and shape and not for specific projectiles.
Like I said, that results on the 25" x 23" plate is damn good and not one specific factor can be blamed for nor being better.
You can enter in custom BC data....you're probably using incorrect data.
The app is rated 4.4 stars, if people were having as terrible of a time you are navigating it, as well as poor results, it would reflect on that rating...
I mean, you're trying to suggest the use of rifle CANT to counter wind drift...I don't think you're in a position to critique Hornady.
Further, Sterlok uses 3DOF, Hornady uses 4DOF, far more accurate....and the more accurate model to that is 6DOF...
"The free app utilizes the Hornady 4DOF™ (4 Degrees of Freedom) Ballistic Calculator, which provides trajectory solutions based on projectile drag coefficient (not ballistic coefficient) along with exact physical modeling of the projectile, its mass and aerodynamic properties. Additionally, 4DOF™ is the first publicly available program that correctly calculates the vertical shift a bullet experiences as it encounters a crosswind, referred to as aerodynamic jump.
Standard ballistic calculators consider three degrees of freedom: windage, elevation and range. But Hornady 4DOF™ adds a fourth degree — the bullet’s movement about its center of gravity and subsequent angle relative to its line of flight — for even greater accuracy."
-Matt
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Matt,
Your numbers from the Hornady app looked substantially different than what I would expect so I was suspicious of them. But I installed the app anyway hoping I’d get better predictions. After playing with it, I’d say that there are some serious math errors in their angular compensation. It’s possible that I’m doing something wrong with the inputs, but I don’t think so.
At this point, I’d agree with Caliber 22s assessment of the Hornady app.
Your numbers from the Hornady app looked substantially different than what I would expect so I was suspicious of them. But I installed the app anyway hoping I’d get better predictions. After playing with it, I’d say that there are some serious math errors in their angular compensation. It’s possible that I’m doing something wrong with the inputs, but I don’t think so.
At this point, I’d agree with Caliber 22s assessment of the Hornady app.
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I just replicated this following real world info into the Hornady app...
At 200 yards, Hornady predicts nearly the same change from -15 to 15 as real world results produced...in fact, it was under, and not over.
However, won't bother arguing, suit yourself.
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Hornady app calculated .22" change from -15 to 15 where real world tests were .38"....where Sterlok shows 0" with the above data on the Sierra 240 gr going 1300 fps at 2,500 altitude.
Think Hornday got a little closer than Sterlok here...and for a free app, if you wanna complain, feel free. If you want better results, there are paid apps that use 6DOF, ranging from $150 to $800.
-Matt
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Applied ballistics is supposed to be a pretty gold standard among ELR community with PB. Kestrel unit is supposed to be the cats meow that goes above and beyond what any app on your phone can do, far more computational power.
Hornady app is very well reviewed, its primarily for their bullets, however you can create custom profiles but their data will not be 100% compared to using their own ammo...and best of all, its free. 4.4/5 stars with 4,767 reviews on google play, and 4.8/5 stars with 34,052 reviews on apple store, in a day and age where maintaining over 4 stars for any app or business is very challenging. I will definitely not take peoples opinions here about the app with more than a grain of salt. To put in perspective, Sterlok has 4.5/5 on google play with 5,677 reviews and only 4/5 stars on apple store with...5 reviews. Applied ballistics = 3.4/5 on google play with 756 reviews and 3.1/5 on Apple with 110 reviews...
-Matt
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