Power Factor

by Vern Walls

AMMUNITION: POWER FACTOR

USPSA uses what is called a "power factor" (PF) to classify ammo. Your ammo's PF 
is calculated by multiplying the weight of your bullet (not the entire round) 
times the velocity of the bullet, and then dividing the result by 1000. The 
minimum power factor allowed is 125 PF. A standard 9mm factory round, as well as 
almost all full power .38 Special factory ammo, will make this minimum PF. Any 
ammunition that meets this minimum PF level and is 9mm caliber or larger will be 
legal to use in any USPSA competition (either the "Limited" or the unlimited 
"Open" gun divisions).

USPSA categorizes ammo into one of two power levels, either "Major" or"Minor". 
(Rule 7.24) For ammo to be considered "Major" it must achieve at least a 175 PF 
and be a minimum diameter of .40 caliber for "Limited" competition (9mm or 
larger for "Open"). The one exception to this minimum caliber for "Major" is the 
.357 magnum revolver, which is scored as "Major" if it reaches the 175 PF. 
Anything that exceeds the minimum 125 PF and falls short of the 175 PF (or is 
less than .40 caliber in "Limited") is called "Minor".

The reason for the two power factors has to do with the scoring of your hits on 
the targets. Since "Major" power loads are usually heavier recoiling loads and 
are hence usually considered to be more difficult to handle, they get scored 
higher on the outer scoring areas than do "Minor" PF loads. The IPSC equivalent 
of a "bullseye" (which is called the "A" zone in IPSC) gets scored the same for 
both PF levels. The only time your ammo's PF makes a difference is on the non-A 
zone area hits (the "B", "C", and "D" zones). As long as you shoot all "A" zones 
(bullseyes), it won't matter which power factor you use. However, it can be 
quite frustrating to see other shooters get one point more for each of their 
"B", "C", and "D" zone hits than you get for yours just because you are shooting 
"Minor".

Still, there are some advantages for a new shooter who reloads, starts out with 
"Minor" loads, and works their way up gradually. Some shooters use "Minor" loads 
because they feel they can shoot quicker and more accurately with the lower 
recoiling loads. If you don't reload, you really don't have a choice - you'll 
have to shoot factory ammo. However, the rules for "Limited" automatically 
result in 38 Super and 9mm being classified as "Minor" regardless of their power 
factor (because of the minimum caliber), while 40 S&W can be either (depending 
on the bullet weight and loading, "Major" usually requires 180-200 gr. bullets), 
and the 45 ACP will almost always be "Major".