First, what is this "Major" in IDPA? I'm not aware of any distinction for IDPA. There is for USPSA. :dunno:
'Major' and 'minor' are probably not the proper terminology for IDPA although they are for IPSC or USPSA.
There are 'Power Floor' values for the various divisions in IDPA and for Standard Service Pistol (SSP), Enhanced Service Pistol (ESP) and Standard Service Revolver (SSR), that value is 125,000 (what I would call 'minor'). For Custom Defensive Pistol (CDP) and Enhanced Service Revolver (ESR), the value is 165,000 (what I would call 'major'). For convenience, divide those values by 1000 and call them Power Factor (125 or 165).
Now, a .40 S&W could run in both SSP and CDP but there would be no point in shooting 165 PF ammo in SSP and 125 PF wouldn't qualify for CDP. The same would be true if somebody wanted to shoot a G21SF (.45 ACP) in SSP - they could download considerably as long as the gun would function. I can't even imagine a 230 gr .45 ACP at 550 fps but the recoil would be LIGHT! The problem would be in getting the gun to cycle as fast as a 9mm.
It has been a long time since I shot in competition and I may never do it again. Nevertheless, I like to keep the power factor requirements in mind when I select a load.
Richard