360pf takes into consideration 16" barreled rifles, shooting standard 147gr ball at 2500fps, which is about what is normal for velocity loss from 20"-22" guns getting 2600-2750. USPSA recognizes 320pf as major, which allows anemic rounds to "MAKE" major and you wind up with the .300 AMU, 7.62x39, 300 whisper or folks trying to get Grendels to make major, none of these rounds are legal in HM, but they get used in USPSA matches to gain major points over minor. If the old major PF of 360 was still recognized they wouldn't stand a chance of making major.
165pf was current standard Major PF for pistol, so they went with it.
going with caliber makes it easier to keep the match moving smoothly, rather than chronoing everyone, that takes a bunch of time, and at least with rifle if you slow your velocity way down to ease the pf then you lose a lot in trajectory, so most shooters do not anyway.
Or we could just say that all HM shooters are soooooo honest it was a waste of time checking everyone when they all were well over the minimum limits, :lol:
trapr