Chris...
Not really, but sorta...
For us guys who handload our 45's, a +P+ is any round handloaded past .45 +P pressures but below 45super pressures. the +P+ loads are loaded in NEW standard 45+P brass (like remmington's nickle brass).
But these are max+ loads and should be treated as such. If you go talk about the specifics on the handloading board you will get lots of disclaimers such as, work up only in the gun you shoot it in, and work up carefully.
As to the HK USP45f, I own one and thats the one I load +P+ for. No ill effects and recoil is surprisingly light. An example of 45+P+ balistics: 45ACP 230gr FMJ @ 1050fps = 560+fpe
JT