Hornady 4DOF vs GeoBallistics Angle Compensation Discrepancies

[crimson702]

Hi all, I was messing around with the Hornady 4DOF app vs GeoBallistics since I run a Vortex HD 4000 GB rangefinder, and noticed some major discrepancies when I started changing shooting angle. As the attached pictures show, the solutions with no angle are relatively close. I believe this also confirms that the inputted variables are all identical.

Once I increase the shooting angle, the 4DOF elevation solutions start to be significantly smaller than the GeoBallistic solutions.

Does anyone have any experience with this, and know which one is more likely to be giving the correct solutions? I do not have access to Applied Ballistics to check the results there compared to these other two solvers, and won't have the ability to test the solutions in the field for some time.

My hunch is the 4DOF app is doing something wrong because GeoBallistics' solution is much closer to the "horizontal" distance solution, but I know that isn't conclusive.

Thanks!

 

[Nicaburns]

I posted a thread recently about inaccuracies with 4dof… I gathered two things from the responses.
1) There are roksliders who are compelled to explain profusely that it is user error.
2) 4dof is unreliable and I no longer use it.

 

[crimson702]

Yes, I saw your post! I’ve also seen a couple other (older) posts regarding 4dof possibly not getting angle compensation right. I was just hoping to get some responses from people who have direct experience using the app with angled shots (since it seems like so many people use 4dof). Or, alternatively, people who have had problems with GB and angled shots.

 

[Nicaburns]

Yes, I saw your post! I’ve also seen a couple other (older) posts regarding 4dof possibly not getting angle compensation right. I was just hoping to get some responses from people who have direct experience using the app with angled shots (since it seems like so many people use 4dof). Or, alternatively, people who have had problems with GB and angled shots.

One of the reasons I’m in the market for a 4000 GB

 

[crimson702]

Overall, I like mine. The best feature it has, in my opinion, is its wind options and on board sensors. Its ability to quickly calculate solutions with a full crosswind mode without using a wind gauge is very convenient.

However, I have found it incredibly sensitive to rain/fog/snow/muzzleloader smoke, and it almost never gives me long distance ranges (i.e. ranges over 1,500 yards). I also have found its compass to be overly sensitive and needs to constantly be calibrated for the wind bearing mode to work.

 

[blick]

Had same experience with 4dof vs revic. 800 yds at 20 degrees, shot both solutions, 4dof was miss the target low, revic spot on.

 

[crimson702]

The solution I was getting was significantly lower than GeoBallastics as well. Thanks!

 

[Quicksilver]

Had this issue with my buddy and his Hornady app. I was running applied ballistics and verified it jbm ballistics. They were less than an inch from each other. The 4dof was waaaaaay off. -34° angle had to be like -21° to match the AB -34° solution. Flat ground they’re within .1mil of each other.

 

[crimson702]

Disappointing to hear that 4DOF has such a big issue with angled shooting. I really like some aspects of the calculator. Thank you for sharing quicksilver!

 

[TradLife406]

Are you guys using zero angle or traditional zero?

The Hornady boys said if you don't use zero angle you'll be off by a bit further out.

Still relatively new to this. Just throwing that out.

I haven't really noticed an issue. I use a Loopy 2800 set to my rifles specs. I just laze the target and input that number. I don't mess with the angle in 4DoF. Seems to work pretty well. My buck was quite a bit below me. 10 ringed him at 750.
Also do some uphill rock shooting at 600. Never had an issue with Hornady.

When I first started shooting a few years ago I had the app all jacked up. Didn't have a large enough sample size of velocities and wasn't using zero angle. A few other garbage values. Got garbage out.

 

[crimson702]

So my understanding is zero angle is great to use in the real world if you have other variables changing between the conditions of when you zero your rifle and another shooting session (pressure, temperature, wind, etc.). This is because these changing variables will change your rifle's impact if you use zero distance, but zero angle can automatically account for them (in theory, a fantastic benefit of using 4dof). In most real world cases, zero angle should be more accurate than zero distance, especially over long distances and when environmental variables change greatly.

However, if your conditions are exactly the same (i.e. you zero your rifle perfectly either using zero angle or zero distance) and then immediately shoot long range, both should give you identical results.

Here, we are discussing using two different solvers (4dof vs. others) but imputing the exact same variables and getting two significantly different elevation results when you increase the angle of shot. Zero distance and zero angle should have no impact on this hypo because none of the variables are changing, and the solvers assume a perfect zero.

I am glad you had no problems using 4dof with angled shooting, but I still think the 4dof is having issues (don't know how long its been happening) if it is having over 1.5MOA difference compared to another solver at 700 yards (roughly a 10.5" difference in impact). This is nothing more than a calculation/solver issue, so hopefully the guys at Hornady can fix it (assuming 4dof is the issue, not the other solvers).