Applied Ballistics for boing

[TJC]

Hi, I'm playing around with Bryan Litz's Applied Ballistics for boing and have an output I'm struggling to understand.

Using a .308 and a 178gr AMAX with a 100-yard zero and 10 mph wind from 3 o'clock produces an output table that reads as below for drop/path:

0 yards: 0.0
50 yards: U0.6 MOA
100 yards: D0.4 MOA
150 yards: U0.2 MOA

I would normally expect to see 0.0 of adjustment required at 100-yards for elevation with a 100 yard zero. Why is this giving me up then down, then up between 50-150 yards ?

To compound my confusion, if I take wind out of the equation by setting that item to 0mph it ends up giving me 0.0 elevation at 100-yards. I would expect to see 0.0 drop irrespective of wind at 100-yards but the larger wind call I make, the more drop is required according to the output.

I emailed Bryan but didn't get a reply and was hoping somone could explain what's going on here ?

Thx

[M99]

Ive just added this bullet in to my AB and come out with a 0 at 100yds - have you got scope height and zero height set?

Adding wind makes no difference on my version.

[TJC]

I have zero elevation correction and zero height offset. I have 2.25 sight height but even if I change that to 10 inches it doesn't change my drop at 100-yards. Weird that wind seems to impact drop and that is with any bullet/load I select.

[M99]

To replicate your figures I neet to put a 125yd zero - ive guessed your m/v at 2600

[TJC]

2700 but I get similar results with other bullets at diff velocities. Weird.

[M99]

Disable spin drift and corriolis effect. This will effect your poi in AB depending on entered barrel twist and direction.

[M99]

Once established that is the cause you can re enable and all is right ;-)

[Swamp Donkey]

Wind from the right will lift the bullet slightly in flight, and lowers from the left. That's your reason.

[M99]

Wind from the right will lift the bullet slightly in flight, and lowers from the left. That's your reason.

Only in rifles with a right hand twist

[TJC]

Spin drift and coriolis disabled. Do you too get elevation adjustment based on wind ? Oddly, it is giving me less elevation adjustment assuming a 500 yrd zero vs a 100 yrd zero for a 10 mph wind. If it were the supposed Magnus effect would it not be greater impact at distance ? Never seen a ballistic app adjust for this before. Thx