Ballistic Apps and the Importance of Accurate Data

[NugginFutz]

Question do you guys use these apps as starting points then tweak the dope card or can you tweak the app for the load.? I notieced today shooting the 308 it was considerably off. We have documented 2 loads out to 500 yds. I had everything punch in but the barrel length. I'm not a computer guy so I might of missed that piece but can't recall were it was a place to enter barrel length. We zero my gredel in at 200 today so that is next on the list. I downloaded the app today. We are going to hit 100 increments out to 500 and then this fall continue to 1,000 or so.

Speaking for myself, I have moved away from dope cards mainly because they are accurate only under the conditions they were developed. I originally had used ballistic programs to create a starting point for my dope cards, but eventually stopped, as their limitations became clear. This is more apparent, the longer the distance at which you shoot.

Ballistic solutions are ideally determined dynamically. Clearly, wind is the most volatile of the variables, but if you consider that 5 degree changes in temperature can have an impact on bullet drops measured in feet, not inches, you realize that data on a card developed weeks or months earlier will only work if you have replicated those conditions. This is why I have transitioned to using either a ballistic program or hand calculations when shooting at any significant distance (500+ yards).

Any decent ballistic app will allow you to enter all the data needed to arrive at a 95% or better firing solution, including your projectile's weight, BC, length and velocity, as well as atmospheric data. For longer range shots, an app which allows use of G7 ballistics (as opposed to G1) can offer more accurate solutions, as they are a better fit.

As far as barrel length being a part of the ballistic solution goes, I am unaware of any of the commercially available programs incorporating that into their solutions. With the muzzle velocity being a fixed value in a given situation, the barrel length really offers nothing I can see. Twist rates might be useful, perhaps, but only for determining the stability of given a projectile. Even that is not accounted for in any of the ballistic programs I am familiar with. I believe most apps assume you are shooting a properly stabilized projectile, as the calculations would become quite intense when trying to account for different modes of stability.

Hope my .02 helps.