The bullet is loaded in the casing at a higher pressure resulting in more BANG and higher velocities adn more lb/ft of energy on impact. +P is regulated as to how much pressure over standard a bullet can be loaded. +P+ is and even higher pressure and not regulated and not widely recommended. run a search. there is more on the board. there is a thread about this right now, cant remember which one tho.
+P is ammunition loaded to higher than standard pressure. Ammuniton that is loaded to +P specs generally produce higher velocity and greater energy. This may or may not, equate to greater "stopping power." +P+ is ammo loaded to even higher pressure/velocity levels. There are standars for +P but not for +P+.
+P is commonly loaded in: .38 special, 9mm, .38 super, and .45 ACP. +P+ is most commonly found in LE ammo in 9mm and .38special.
Keep in mind that to double your speed (in any context) that you must increase your energy input by four times and that your energy is proportional to the pressure. Therefore, +P(ressure) is kind of a pandoras box. Keep in mind that increased pressure and velocity means more wear.
An example of +P versus standard velocity:
Remington 9mm 115gr JHP
Standard 1155Fps 341Ft. Lbs
+P 1250Fps 399Ft. Lbs
58 Ft. Lbs may seem like a lot of a difference
but 83 Ft. Lbs of energy is dissipated by the +P load just traveling through 50 yards of air!
Source: 1999 Shooters Bible, Remington Ballistics Chart.
Hope this provides a more scientific view of the +P issue, without being vague or confusing.
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