Ballistic program discrepancy

[1time]

I am using Ballistic FTE on an Iphone. I am using local weather for all inputs(automatic in software)and phone GPS for altitude. My bullet speed is from a chronograph. Ammo is Blackhills 75 grain Horndady Match.

Sight in is at 100 yards. At 300 yards the drop is 1.25 Moa more than FTE says it should be. At 500 yards the drop is 3 MOA more than FTE says. What should I adjust to try and get FTE inline with actual drop?

 

[doc76251]

Re: Ballistic program discrepancy

Check and see that your scope is doing what you think it is.

Cheers.

Doc

 

[Woj8541]

Re: Ballistic program discrepancy

Unfortunately there isnt an easy answer unless you provide the specific inputs you've provided the software. It could be something simple, or a combination of about a dozen parameters that haven't been inputted correctly. Don't get me wrong, this is most likely no fault of your own. Ballistic solvers are computer programs which only provide good outputs if given the proper inputs. They are very specific and one small oversight can show the very discrepancy you're describing.

Doc's suggestion of checking your scope's tracking is pretty much the top priority. This is a step that I perform before doing any POA/POI proofing with a solver. It's going to save you valuable time, ammunition (money), and frustration.

Cheers

 

[phillietimothy]

Re: Ballistic program discrepancy

Does your software provide "trajectory validation"? This feature allows you to input actual drop data at various distances, it then adjusts fps or other variables until your ammo matches real world results. Just a thought.

By the way, the more different distances you shoot, the more accurate trajectory validation programs will be.

Tim

 

[arborpro]

Re: Ballistic program discrepancy

along with the above advice. are you shooting level at those ranges is your scope canted? 1st i'd box test that scope and see if it is functioning correctly. then id see what your comeups should be for your 500yard zero and check that against your program for exactly 100 yrds and see that your scope will move your bullet impact the same as your program says for 100 yds. now this must be at exactly 100 yrds. you can go to G7 ballistics http://www.gseven.com/ if you need a true up calculation for either BC or velocity. it should be done at a range where your bullet is still supersonic so Id go out to 700-800 yds if you have that availble to obtain zero at that range then use that info for your truing. I think thay have a video that will help you.

 

[1time]

Re: Ballistic program discrepancy

Thank you. I'll try the box test to see where I am.