Power factor?
- Thread starter Axis II
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N555
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Certain matches don't allow the use of powder puff loads.
IWAC
Member
When I used to shoot IPSC, none of my loads, which were what I carried then, would make major, but I found if you shoot well, it's not much of a handicap. They were not "bunny fart" loads, either! Me and my six shooter against the autoloaders...I just wanted to put myself in a high-stress situation, so I wasn't a serious competitor, but never finished less than in the middle of the pack, and had a good time! 
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fxvr5
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Power factor means the bullet must make a certain speed to be eligible for scoring. In the 9mm, for example, the power factor minimum might be 125. Power factor is calculated as the bullet weight times velocity divided by 1000. It's easier to calculate it as 125,000/147 for the required speed. For a power factor of 125 a 147 grain bullet must be going: 125,000/147 = 850.340 fps. Since many calculations drop the decimal, the answer is no less than 850 fps. Most shooters load to a 30-50 fps speed over this to have a margin of error.
Is there a reason why?
eddiememphis
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To even the playing field and have recoil control play a factor in the game.
.38 Special
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Reduced recoil reduces split times, so where allowed, shooters will reduce their loads to the ragged edge of safety and reliability. See: Cowboy action, see: PPC. For organizations trying to maintain at least the appearance of "practicality", a minimum power floor is necessary.
Palladan44
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The "P" in practical.
To simulate "business" loads
lordpaxman
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Actually USPSA drops the decimal after the bullet weight x velocity/1000, so 147x850/1000 = 124.950 and equals 124 PF which is now sub minor. You’re just shooting for score. I shoot for a 5% overage just to try to make chrono.
USPSA and IPSC have minor PF of 125 and major PF of 165. IDPA has PFs for different divisions. SCSA only specifies the bullet has to hit the steel plate and it’s a visible score, you don’t have hear a ring
. In USPSA certain divisions also award you more points in certain areas of the targets if you shoot major PF vs minor PF. Think of it as damage from an 9 vs an .45. And if those yahoos would only allow that in LO, we’d have a nice new year.I won’t get in to certified ammo.
In addition to having different divisions that level the playing field for guns, and classifications that level the field for your abilities, the PFs attempt to duplicate common factory loads. Chrono some 115gr WW white box and in my gun it’s right around 126.
N555
Member
Some powder puff loads can be extremely accurate. Such as when 45acp is loaded 4.5gr of wst under a 230gr bullet, makes the bullet do about 700fps. Very accurate, low recoil, allows real fast follow up shots but not practical for a self defense load.
mcb
Member
USPSA also rewards shooting ammunition with a greater recoil in many divisions.
Open, Limited, Limited-10, Single Stack, and Revolver divisions can all be shot with a Major (165 PF) or Minor 125 PF) On paper targets, Major is scored Alpha 5pts, Charlie 4pts, Delta 2pts and Minor is scored Alpha 5pts, Charlie 2pts, Delta 1pts. In addition since steel has to fall to score a Major gun will often knock a steel target down with a low or edge hit that the same hit with a Minor gun might have left the steel standing.
Production, Carry Optics, and PPC are all scored Minor power factor only.
Open, Limited, Limited-10, Single Stack, and Revolver divisions can all be shot with a Major (165 PF) or Minor 125 PF) On paper targets, Major is scored Alpha 5pts, Charlie 4pts, Delta 2pts and Minor is scored Alpha 5pts, Charlie 2pts, Delta 1pts. In addition since steel has to fall to score a Major gun will often knock a steel target down with a low or edge hit that the same hit with a Minor gun might have left the steel standing.
Production, Carry Optics, and PPC are all scored Minor power factor only.
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eddiememphis
Member
230 grains @ 700 fps is a 161 power factor.
As the others mentioned, Power Factor is just a way to quantify the momentum of the projectile in order to verify it meets minimum requirements for the product of projectile weight (in grains) and muzzle velocity (in feet per second) divided by 1000 for a specific organization and division. It was initiated with IPSC, than carried over into USPSA, and IDPA uses it as well. It's only relevant if 1) you shoot one or more of those games, and 2) you're at a match in which they have a chronograph station. Well, I suppose it's relevant if there is no chrono such as at club level matches, but then you are essentially on the honor system.
For IDPA, it's just a minimum requirement for each division. For IPSC and USPSA, there are minimum values for minor and major PF scoring. Major gets more points for non-A hits compared to minor.
