"...Usually it means High Power..." 'HP' only means Hollow Point to the rest of us. Unless you're talking to computer techies. Then it means Hewlett-Packard. snicker.
Anyway, compressed loads are loads with enough powder that the bullet pushes said powder down when seating. A particular powder, like IMR4227 in .30 Carbine, is compressed. That starts several grains below Max. Currently 14.5. Compression begins at about 13.5 or thereabouts.
There will be a 'c' after such data in your manual. Nothing to worry about though.
As mentioned, it'd be decidedly unusual for any handgun cartridge to be compressed with typical powders. Although max loads of 20.7 and 21.0 of IMR4227 with a 325 and 330 grain bullet in .44 mag is compressed, but not a 355 at 19.. According to Hodgdon's site.
Anyway, compressed loads are loads with enough powder that the bullet pushes said powder down when seating. A particular powder, like IMR4227 in .30 Carbine, is compressed. That starts several grains below Max. Currently 14.5. Compression begins at about 13.5 or thereabouts.
There will be a 'c' after such data in your manual. Nothing to worry about though.
As mentioned, it'd be decidedly unusual for any handgun cartridge to be compressed with typical powders. Although max loads of 20.7 and 21.0 of IMR4227 with a 325 and 330 grain bullet in .44 mag is compressed, but not a 355 at 19.. According to Hodgdon's site.