.45 G.A.P. pressure is SAAMI-established at a maximum of 23,000 psi, but was tested up to 35,000 psi. Actual pres*sure of the released round runs between 19,900 and 20,500 psi to be "on the safe side."
I stand corrected ..... .40 S&W runs to 33K ...... .45 GAP is equal to .45 ACP+p pressure wise.....
but.....
The .45 GAP has the same pressure issue (although to a lesser extent) that the .40 S&W does, particularly with 230 gr bullets:
Even in the same firearm, with the same components, cartridges with low powder capacity and high operating pressures, such as the .40 S&W, have been shown to have a significant increase in pressure with very minor differences in bullet seating depth. One example in .40 S&W demonstrated a 20% pressure increase with a 0.05 inch (1.2 mm) change in seating depth.*
TANSTAAFL, especially in physics.
The question is:
Is .45 ACP performance, at the cost of .45ACP+p pressures, with some of the same case capacity/pressure issue of the .40 S&W (compounded by the unsupported chamber of the Glock handgun .... true, pretty much a non-issue for folks who don't reload, but I do......) worth .140" OAL? Capacity (dictated by cartridge diameter) will be the same, in similar pistol designs .... The Market, the Ultimate Arbiter, says no.....
..... you pick your choice, pay your money and take your chances ..... Me, I'd buy a .45 GAP EMP before I bought one in .40 S&W, but such a thing is not made.... and by the looks of things, I'd have to hoard brass if I did.....
*Can you say, "Bullet setback?" .... I knew you could!....