The 45 gap round shoots faster and obviously hits harder than standard 45 of the same bullet weight
Not quite... The 45 GAP has a shorter case and less case capacity than the 45 auto. In order to obtain velocities similar to a 45 auto, the GAP has to be loaded to near maximum pressures. Most cartridge manufacturers list the GAP at about 15-20 FPS faster than the AUTO- yes it might hit harder, by a ft-lb or so[:-]
The 45 auto has legs to grow where the GAP peters out. When the AUTO is loaded to its full potential (called +P loads) its at least 100 fps faster than the maximum GAP loads. Now you are actually talking about a significant difference in hitting power
If it catches on it will overtake the old 45 but there is too much history behind the 45acp to let it go just yet.
The only reasoning for the GAP is to put .45 auto power in a pistol that has a frame to accomodate a 9mm. I.E. you get more punch in a smaller package. Springfield has recently come out with a version of their XD where they shaved off enough material from the frame, and engineered everything short and narrow enough that it shoots 45 auto in a gun no bigger than a what would be required for a 9mm both in thickness and size. If it weren't for the popularity of Glocks in general, the GAP would be well on its way down the obsolescence path if it isn't heading that way already. The .357 SIG has been going that direction for awhile- it offers near 357 magnum performance in a semiauto. The 357SIG is another very expensive round that has the extra bonus of being a bitch to reload. One of the advantages the GAP still has is that at least its easy to reload.