Ballistic Calculators - Elevation

[rlsmith1]

I'm a flatlander but was thinking today about how nice it would be to shoot at 5k+ altitude for the increased bullet aerodynamics.

My question is, what ballistic calculators (if any) would provide an accurate solution for a 1,500 yd shot that was taken at 8k altitude but the target was at 5k? This is obviously a very complex shot as the shooter would be shooting about 40 degrees down, but mountains are steep and I'm sure it happens. The reason I ask is according to JBM, a 1,500 yd solution at 8k is 16.6 mil while the solution at 5k is 18.1 mil and the bullet is starting to go transonic (6.5 CM with 140 gr hybrid @ 2550).

Would love to hear anyone's real world experience with similar scenarios and I understand there is so much more to solve for at 1,500 but being off by 2.5 mil just due to altitude could be huge and confusing.

 

[6.5SH]

Try JBM again with the slope angle there.

 

[rlsmith1]

Nice, thanks. I thought there had to be a solution out there but have zero experience at elevation, let alone changing elevation. I assume this calculator is about as good as the data that gets put in?

 

[6.5SH]

Nice, thanks. I thought there had to be a solution out there but have zero experience at elevation, let alone changing elevation. I assume this calculator is about as good as the data that gets put in?

That is true for all calculators and is the main issue with predictions not being close to reality. This can be from assumptions on key items such as; not really being zeroed, the zero range being different than what you think, distance being shot different, scope clicks a different value etc.

 

[ptosis]

Almost all of my long range shooting happens in the mountains, simply because in our parts 1km+ of flat land is a too precious commodity to build a shooting range on. So...

https://geladen.ch/en/inclined-fire/ may give bits of answers.

and long range shooting at 40° must be extremely rare. In fact, shots of 30° are already extremely rare, and subjectively appear as a very steep angle. I think the most extreme I had the occasion to shoot personally was 27° downhill, but usually it stays within ±20°.

Ballistic calculators usually give perfectly valid results, just make sure the engine takes into account changes of atmosphere along the bullet's path. The way to check it is to see the difference of elevation to dial when shooting uphill and downhill. With the same angle (e.g. 30° uphill and 30° downhill) the difference should be very small -- at most one or two clicks up to transsonic. If there is a lot of difference, the calculator may be fine in flatlands, but no good with serious inclinations.