There seems to be some confusion regarding the typical trajectories of different 9mm Luger bullets. So, let's look at the projected trajectories of some typical cartridges.
The following external ballistics graphs were generated in the current version of QuickLOAD/QuickTARGET and confirmed by the JBM Ballistics Trajectory (Simplified)
calculator.
Let's assume that I have a G17 with adjustable sights and want to adjust the elevation such the the rise and fall of the bullet is equidistant relative to the line of sight (LoS) for a distance of 100 yards.
For a 147 gr Speer Gold Dot and a muzzle velocity of 950 fps, the projected trajectory is as shown
here. Note that, relative to the LoS, the rise and fall of the bullet is approximately 3.5". For reference, the sights must be adjusted to elevate the muzzle approximately 17.2 MOA.
And, for a 115 gr Speer Gold Dot and a muzzle velocity of 1150 fps, the projected trajectory is as shown
here. Note that, relative to the LoS, the rise and fall of the bullet is approximately 2.5" and the sights must be adjusted to elevate the muzzle approximately 12.5 MOA.
As may be noted, under these conditions, at the peak height above the LoS, the 147 gr bullet flies about 1" higher than the 115 gr bullet. However, note that the muzzle is elevated higher for the 147 gr bullet relative to the 115 gr bullet to achieve the same second zero crossover of 84 yards.
That being said, my guess is most shooters (including me) use fixed sights with standard heights, which elevate the muzzle of a G17 approximately 8 MOA... and the projected trajectories are
hereand
here for the 147 gr GD and 115 gr GD bullets, respectively. Also, for comparison, the projected trajectory for a 124 gr Speer Gold Dot and a muzzle velocity of 1100 fps is as shown
here.
Under
these conditions, at the peak heights above the LoS, the 147 gr and 115 gr bullets fly 0.4" and 0.8", respectively, above the LoS and the 147 gr bullet flies about 0.4"
lower (not higher) than the 115 gr bullet. Also, note that the second zero crossovers for the 147 gr and 115 gr bullets are
35 yds and
52 yds, respectively. And, under 45 yds or so, the 147 gr bullet flies a bit 'flatter'.
With the same POA and muzzle elevation (that is, with fixed sights or with adjustable sights at the same 'setting'), given similar nose profiles, slower bullets, regardless of weight, will always fly lower than faster bullets.
Physics is physics. That won't change... and bullets will fly accordingly.
