Originally Posted by Brian.Samson
Under 15 yards (no matter what the angle) 0-90 degrees up or down, the difference in trajectory is so small you won't be accurate enough to be able to tell (if we're talking purely ballistics).
If you've witnessed anything different, it's not ballistics that's the problem it's likely to be that at extreme angles, the problem isn't knowing where to aim, it's keeping your crosshairs steady and dealing with cant / parallax error etc.
Unless you're shooting a springer and they do very weird things.
I'm with this ... and especially the springer thing.
This is another one of those subjects that attracts the most common of all internet air rifle board issues ... total b0ll0x.
Technically and theoretically the facts are that, at steep angles, up or down, you should aim a tad lower at targets beyond a certain distance ( we seem to have settled on 15 yards ). Like Mr P said ... edge your bets and for FT dial in and aim lower than centre but inside kill and you've got a good chance. It gets a bit weirder for HFT shooters where you are picking an aim point and especially high angled 15mm kill shots in that sub 20 yard region.
Like someone else has mentioned ... I would go to the range and put some targets at elevated angles at various distances and see where your aim points/poi's are. I'm not suggesting that you will prove ballistics wrong. I'm saying that, far more than the ballistic story, you will probably get differing points of impact, because of the way the angle is making you shoot. Cant, PA error, butt sitting differently in your shoulder, fore hand placed differently on front of stock, extra tension in back muscles etc ( as Bri will know ... those last few play havoc with springermen more so than pcp's ).
So the under 15 degrees and yards is a good start. The Mr P just aim a tad lower, but inside kill, at the longer ones is another top tip, but I would check how the angles affect YOU. You then try and eliminate or reduce how you are shooting differently at angles.