There is nothing flat about any airguns trajectory. But I guess we could compare rainbows. When I saw what I was dealing with trajectory wise no matter how fast we made our guns or what projectile we shot, my focus was solely on the tightest consistent groups I can achieve at 80-100 yards. I would rather make elevation and windage adjustments for a slower consistent tack driver than a temperamental speedster. Now when we keep the distance considerably under 100 yards, yes we have some pretty flat shooting airguns. Compared to my Sheridan Blue Streak pumper.
+1, agree with the above. One thing (not in the above, but mentioned a few times on some entries in this post), is the misconception that the faster the projectile goes, the less it is affected by the wind. It does seem to make common sense, and I've been in quite a few online discussions regarding this, plus picked up a few trolls in the process. Safe to say that all you really need to do is plug into Strelok Pro or Shooter.
A Pellet at 1050 FPS, same distance, and same side wind, and at 880 FPS (a common pellet speed), and see how the total wind drift compares. At 100 yards and 10 MPH wind, the SLOWER pellet (in this case, a .25 King Heavy) drifts about 7 inches, and the much FASTER pellet drifts about 8 inches. How can this be you ask? The faster one spent less time in the wind than the slower one... Hint: it is a function of the RATE at which the pellet slows down, not the gross speed.
For slugs, the difference isn't much, for the .25 NSA 38.9 grain at 965 FPS and the same slug at 1075 FPS in the same conditions, the faster one drifts about same as the slower one... So no benefit as far as wind drift for going much faster. Yes, of course the faster one will drop less and have a "flatter" trajectory... But lets take a look at that so called "flatter" trajectory from a practical standpoint, say 250 yards, on a gun with a 50 yard zero. So at 250 yards, lets look at how much (or not) the flatter trajectory benefits the shooter.
Speed 245Y, 250Y, 255Y
1075 85 in 89 in 94 in
965 105 in 110 in 116 in
Wow, you might say, that's about 20 inches difference!!! But what does that do for you? What this tells me is that if I'm shooting at a ground squirrel with about a 2 to 3 inch KZ (maximum),
in both cases if I'm off by 5 yards ranging I miss... And since the wind drift difference is negligible, is there really any benefit to jacking your speed up to over 1050 FPS, or even over 1000 FPS? To me its a no brainer and the speed that the gun is most accurate at and most easy to shoot accurately should be your choice.
Even with your heavy raw on gusty wind, no way with 18gn pellet 
