Velocity does not determine a "Hot" load.
Presure in excess of SAAMI standards is technically a +P(resure) load. SAAMI does not establish a +P level for all cartridges. The increased presure level is on the order of 10% on the cartridges I have researched. I have never seen SAAMI +P+ presure standard data.
For a politically correct interpretation of +P loads, call 1-800-IMRDATA or any of the Powder/Bullet manufacturers tech hot lines to get the company line.
I can tell you from my imprecise, small sample, with assumption about powder burn rate, mathematical investigation of one large manufacturers +P and +P+ loads: +P is less than 7% increase in powder charge over SAAMI max. +P+ is less than 12% increase in powder charge over SAAMI max. Many handloaders push the envelope further than factory loads.
McNetts loads are the top of the heap in velocity, power, and momentum. They are not +P loads generally, though his 180gr BJHP 10.8gr 800-X is.
Last edited by bdc; 12-06-2003 at 15:38..