I personally can't stand 115 grain bullets, at least in hollowpoints, and if you want pointed style FMJ, you prolly need 124s.
The problem, the way I heard it explained, is that bullets go through a temporary de-stabilization when they drop under the sound barrier.
That's why FOR ME, I have the best accuracy results with magnum handguns, anything around 1200-1300 FPS, or really light loads that were subsonic to begin with.
In other words, big and slow= 230 grain (800 FPS or so...).45 acp heavy bullet at below speed of sound. Lobbing trajectory, predictable results, accurate.
Light and fast=125 grain .357 magnum light bullet at speeds that are likely to STAY supersonic until the bullet gets to the target (1450 FPS!!). Flat (For a pistol.) trajectory, devastating results, accurate.
The problem for me is 'compromise' bullets.
Take .40, for instance.
A 155-165 grain bullet, at 1150 FPS is likely to start out supersonic, and mid-flight drop to subsonic about the time stabilization is critical. (Provided you shoot at 25 yards.)
Avoiding the hypothetical de-stabilization, among other reasons, like bullet design, bearing surface, intended use, feeding in picky semi-autos.
They, and many more are very good reasons that you'll find many bullet weights in most calibers.
Some of the bullet weights don't always appear necessary, but to some people, your choices aren't going to serve their needs.
I have not noted any destablization problem of a 140 grain bullet (.357 mag) running at 1400 fps down range of 100 yards shot from a Ruger 6 1/2" barrel.
L O L I love to argue. It gets my blood pressure up to where I can measure it(120/70 age 62). 
L O L
