AB way off compared to other calculators and real world.

[ssteve]

Been playing with 4dof, kac bulletflight, bullet drop and then I just spent the $30 to play with Applied ballistics. mostly to gain access to their bullet library.

rifle I am shooting is a bergara 22" 6.5cm.
load is barnes 120gr ttsx with an advertised bc of 0.412, norma brass, 43.8gr of h4350 and magneto speed is giving me 2960fps.
sight height is 1.9", zero is 100yrds.
environment 1500ft 28.23 2mph wind at my back

100 yard zero is solid.

shot the rifle at 677 yard on a 12" plate. impacts dialing 3.6 mils.

kac bulletflight gives me 3.5 mils
bullet drop app gives me 3.9 mils
4dof app gives me 3.67

Applied ballistic with their BC from their bullet library gives me 4.7 mils. If I put in a g1 bc of 0.412 then it drops to 4.5mils

At 200 yard at my local range, I am getting about .3 mils drop and at 300 I am getting about .9 mils.

bulletflight shows .4 at 200 and .9 at 300
bulletdrop .4 at 200 and 1.0 at 300
4dof .29 at 200 and .81 at 300

So for what my rifle is actually shooting, 4dof seems to be about spot on to the 670 I have taken it to, but my question is why is AB so far off with all drag models? I even purchased their custom curve for that bullet and its the same data, about 4.5 mils.

 

[_Windrider_]

Been playing with 4dof, kac bulletflight, bullet drop and then I just spent the $30 to play with Applied ballistics. mostly to gain access to their bullet library.

rifle I am shooting is a bergara 22" 6.5cm.
load is barnes 120gr ttsx with an advertised bc of 0.412, norma brass, 43.8gr of h4350 and magneto speed is giving me 2960fps.
sight height is 1.9", zero is 100yrds.
environment 1500ft 28.23 2mph wind at my back

100 yard zero is solid.

shot the rifle at 677 yard on a 12" plate. impacts dialing 3.6 mils.

kac bulletflight gives me 3.5 mils
bullet drop app gives me 3.9 mils
4dof app gives me 3.67

Applied ballistic with their BC from their bullet library gives me 4.7 mils. If I put in a g1 bc of 0.412 then it drops to 4.5mils

At 200 yard at my local range, I am getting about .3 mils drop and at 300 I am getting about .9 mils.

bulletflight shows .4 at 200 and .9 at 300
bulletdrop .4 at 200 and 1.0 at 300
4dof .29 at 200 and .81 at 300

So for what my rifle is actually shooting, 4dof seems to be about spot on to the 670 I have taken it to, but my question is why is AB so far off with all drag models? I even purchased their custom curve for that bullet and its the same data, about 4.5 mils.

Does the MV match?

 

[aslrookie]

I’ve had no issues with AB. I don’t use the bullet library. My truing has been within a few fps of chrono numbers.

 

[ssteve]

Does the MV match?

yes. used from 2940-2980 and its no where in the ballpark.

 

[_Windrider_]

yes. used from 2940-2980 and its no where in the ballpark.

Youre missing something in the setup somewhere. Can I put up screenshots of the rifle and ammo setup

 

[ssteve]

Yeah I’m sure I’m missing something.

 

[_Windrider_]

Yeah I’m sure I’m missing something.

Ok. In your zero atmosphere, when pressure is absolute is selected leave altitude empty.

In your environmental for the shot, you have station pressure entered but did not select pressure is absolute, again leave altitude empty.

 

[ssteve]

Ok. In your zero atmosphere, when pressure is absolute is selected leave altitude empty.

In your environmental for the shot, you have station pressure entered but did not select pressure is absolute, again leave altitude empty.

Didn't change the drop, just populated my local weather station stuff which isn't far off where I was shooting so it stayed 4.7mils.

 

[Dthomas3523]

So, your DA is around 1500 or so?

I can’t get StrelokPro or my 5700 elite to even get close to 3.6 with those numbers.

My very trued data for 108 eldm and 105 hybrids at around 3k fps are only around 3.7/3.8 at 677 with 1500 DA

 

[Dthomas3523]

And these are bullets with over .5 g1 and just under .3 g7.

 

[Eostech]

trying Hornady, AB and Lapua ballistics, they are all around 4.5 MIL with those inputs.
As I think Dthomas3523 points out, thats awful flat shooting for a pretty low BC at under 3000 FPS.

 

[AIAW]

Disable "Enable Zero Atmosphere" also. Not needed for a 100 yard zero.

Just out of curiosity, are the others apps using the exact same advertised BC?

 

[ssteve]

Here’s my 4dof screen shots. Not sure why it’s defaulting to such a large angle but

 

[_Windrider_]

Disable "Enable Zero Atmosphere" also. Not needed for a 100 yard zero.

Just out of curiosity, are the others apps using the exact same advertised BC?

I tried this as well. I couldn’t get AB any lower than 4.4.

 

[AIAW]

I tried this as well. I couldn’t get AB any lower than 4.4.

Damn...

 

[_Windrider_]

Here’s my 4dof screen shots. Not sure why it’s defaulting to such a large angle but

When I use 4DOF, I get 4.48 Mils at 667 yards.

 

[Dthomas3523]

I’m still confused how you’re getting 3.6 real world impacts with that bullet

 

[beretta_man11]

I’m still confused how you’re getting 3.6 real world impacts with that bullet

maybe the other apps have been 'trued' using the error in the scope? He thinks he's dialed 3.6 but internals moved to 4.7? That's a leap, but still a thought.

 

[aslrookie]

maybe the other apps have been 'trued' using the error in the scope? He thinks he's dialed 3.6 but internals moved to 4.7? That's a leap, but still a thought.

That would be one hell of a tracking error lol

 

[jrayw02]

If reticle allows try holdover instead of dialing to confirm

 

[Lowlight]

JBM which is a pretty clean program with next to no flourishes shows 4.7 too

A full mil is huge, are you sure you are not skipping the rounds in when you hit, or are you grouping on the target?

Also I agree, back it up with the reticle to confirm.

 

[seansmd]

is that shooting angle of -16 degrees real? if you are using the phone app you can overide it, it uses the phone sensore and where you aim/hold the dof.

 

[Milo 2.5]

Yeah I’m sure I’m missing something.

Powder temp, check your first 2 boxes of that post, disable powder temp before calculating. Or match them.

 

[Dthomas3523]

Powder temp, check your first 2 boxes of that post, disable powder temp before calculating. Or match them.

What would explain him getting a mil less real world data though?

I don’t want to doubt him in an insulting way, but that’s kinda nuts.

 

[Lowlight]

Depending on the target placement and size,

I have seen guys skip a round into them with less dope thinking it was right.

Something is not right, and I doubt it's 100% software, it's probably a combination of things including the shots taken.

In this case, I would say AB is probably correct. Unless the range has some weird anomaly.

I would say, go the range without a computer, dope the shot at 3.6 Mils and fire a group on steel, and then add 4.6 and see what happens, in this case, 4.6 vs 3.6 with a 6.5CM would mean a 100 yard difference.

6.5CMs move about .8 per 100 yards to about 800 after 300.

 

[Milo 2.5]

What would explain him getting a mil less real world data though?

I don’t want to doubt him in an insulting way, but that’s kinda nuts.

I went through this last Friday with a friend, not a mil, that is huge, but I believe in my situation, the guys zero was off by 40 yards(200 zero).
I have never manipulated an app to match up like we did, I even paid for strelok pro, to have his app on my phone. Maybe tomorrow we can go back out and settle this. He wants to hunt, hence the 200 yard zero, and his logic works great to 325 yards before he dials.
As you know, and we all do, most of the times with these issues, inputs are incorrect, somewhere.

 

[Milo 2.5]

No one has asked, is the target actually at 670?

 

[Dthomas3523]

No one has asked, is the target actually at 670?

If everything is correct, I’m betting ~600yds actual.

 

[AIAW]

If everything is correct, I’m betting ~600yds actual.

I was sort of thinking that too, but he was getting good data/impacts with the other software(s). Still, your theory definitely could be the ticket there if there was some target confusion, etc.

 

[ssteve]

Issue found! So I was getting hits cause my calculations were correct at the time of sending rounds down range.. And I mean down down range cause I was shooting at a steep decline down a hill. For some reason when I was comparing things and setting the 4dof stuff at home it was not coming off the -16* angle. I still cant get it to so I deleted the app and reloaded it. Got all the data back in and just used my current atmosphere and it gave me 4.6mils at 0* incline/decline. Set t to -16* and its back to 3.7 but also now whenever I hit save it crashes the app. Additionally the app would not show a bunch of text with apples new dark mode enabled.

 

[_Windrider_]

Issue found! So I was getting hits cause my calculations were correct at the time of sending rounds down range.. And I mean down down range cause I was shooting at a steep decline down a hill. For some reason when I was comparing things and setting the 4dof stuff at home it was not coming off the -16* angle. I still cant get it to so I deleted the app and reloaded it. Got all the data back in and just used my current atmosphere and it gave me 4.6mils at 0* incline/decline. Set t to -16* and its back to 3.7 but also now whenever I hit save it crashes the app. Additionally the app would not show a bunch of text with apples new dark mode enabled.

Wait. So is the 677 yds the line of sight distance or the horizontal distance?

 

[ssteve]

Distance from me to the target. Ok so here’s my redneck range finder since my dad has mine out hunting. Took my drone and flew it from my location to the target which was 2031 feet from my shooting location.

 

[AIAW]

So basically software, but not really software...

 

[ssteve]

Yes, but no. kinda.

 

[spife7980]

Distance from me to the target. Ok so here’s my redneck range finder since my dad has mine out hunting. Took my drone and flew it from my location to the target which was 2031 feet from my shooting location.

Geoballistics uses GIS/satellite to get you your distances... its pretty good too. https://geoballistics.com/
This is real reason I use it instead of other apps. Its damn handy. And as Frank said the JBM engine is pretty clean.

 

[Dthomas3523]

Issue found! So I was getting hits cause my calculations were correct at the time of sending rounds down range.. And I mean down down range cause I was shooting at a steep decline down a hill. For some reason when I was comparing things and setting the 4dof stuff at home it was not coming off the -16* angle. I still cant get it to so I deleted the app and reloaded it. Got all the data back in and just used my current atmosphere and it gave me 4.6mils at 0* incline/decline. Set t to -16* and its back to 3.7 but also now whenever I hit save it crashes the app. Additionally the app would not show a bunch of text with apples new dark mode enabled.

So, your actual distance was 677yds and you were shooting at around 30 degrees or so? That’s what all my calculators need to get close to 3.7 with that round at 677.

 

[seansmd]

Geoballistics uses GIS/satellite to get you your distances... its pretty good too. https://geoballistics.com/
This is real reason I use it instead of other apps. Its damn handy. And as Frank said the JBM engine is pretty clean.
View attachment 7158383

Does this show angle vs LOS?

 

[spife7980]

Does this show angle vs LOS?

Wouldn’t angle be your line of sight? Or do you mean angular vs horizontal distance differences?

For elevation you’d want the horizontal distance. The satellite should accomplish that. The windage may be a tad off for extreme angles but that’s something I can really speak to.

 

[seansmd]

I was wondering if the App map feature will show the elevation change, equating to the -16 degrees that was part of this shooter's mis-aligned dope. I think it will give you the elevation at the shooter pin, and the elevation at the target but not the angle. So at the end you end up with the horizontal distance, similar to what his drone method gave him, but did not give him the angle.

the Hornady app will capture the angle using the phone, and he somehow captured that in his app previously in the thread.

 

[seansmd]

So, your actual distance was 677yds and you were shooting at around 30 degrees or so? That’s what all my calculators need to get close to 3.7 with that round at 677.

I think it must be a combination of inaccurate distance(captured by drone) and no angle in the solution?

 

[ssteve]

I think it must be a combination of inaccurate distance(captured by drone) and no angle in the solution?

Pretty sure the distance was accurate otherwise I wouldn’t have consistently hit with the come up the 4dof gave me. It was just I didn’t realize there was such. Large angle when I inputted the data into the other solvers. I have used the drone to calculate distance many things and I would trust it over most range finders. Ill go back out there and run the data again when I have my range finder back and then get down the hill some to see how the angle affects it if I am close to level with the target. my assumption is that I will be around 4.4 mils with 0 angle.