Power factor helps determine what class you will compete in. Major or Minor for example. 9mm would usually be a minor and 40+ usually major. Though it's possible to get loads that aren't.
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vlavalle
Single-Sixer
'Major' and 'Minor' what? Is this some sort of official classes of shooting at real shooting ranges?
The use of major and minor power factors started with Jeff Cooper and IPSC way back in the 70's or perhaps even earlier as a way to measure the momentum of a cartridge. To score major a round had to factor at least 175 using bullet weight X velocity. A cartridge scoring minor had to score a minimum of 125. In target scoring on the IPSC target both rounds would receive 5 points for a center hit (A zone) but the minor round received a lower score for hits in the B,C, and D zones than the major cartridge (google IPSC target scoring rings for an illustration). As an example a 200 grain bullet at 900 FPS has a power factor of 180 while a 115 grain bullet at 1100 FPS had a PF of 126. The purpose was to reward the more powerful but heavier recoiling round while penalizing the lighter, softer shooting rounds. Bullet diameter did not play into the measurement.
As noted above this method of "power" calculation has been in use for at least 50 years among those shooting in the "practical" shooting sports.
contender
Ruger Guru
valvalle,, you have uncovered something new to your shooting knowledge,, AND by doing so, have allowed others who haven't heard of "power factor" or it's use to get a good overview of what it means.
The explanations above delve into most of it,, and even truly point to the more technical info. All very good info for those unfamiliar with it.
As a long time USPSA competitor,, who prior to 1998 had very little knowledge of it as well, I got introduced to it's use. It is used in real gun competitions as a way of trying to level the playing field for competition. It's not a computer game thing,, it is real world.
When I started in 1998,, I discovered that USPSA had a way of "measuring" felt recoil by using what is known as power factor. The basic formula is "Bullet weight, X velocity, divided by 1000." And USPSA had what is known as "Major" & "Minor" power factor (p/f). It used to be,, for competition, the dividing line was a p/f of 175. Many years ago,, for the USPSA game,, it was reduced to 165.
When I started in USPSA,, I was using a 1911 in .45 acp. The most common bullet is a 230 grn round nose. Factory ammo usually chrono's at about 850-925 fps depending upon the maker. Using that, let's look at a factory p/f. Using a 230 grn bullet & the velocity of 850, we get; 230 x 850 =195500. Divide that number by 1000, and you get a p/f of 195.5. Or 20.5 points above the threshold required to make "Major." In USPSA,, the SCORING on a target is divided into different levels of points depending upon where you hit a target. No matter what p/f you are shooting,, a hit in the "A" zone gives you 5 points. BUT,, outside the "A" zone the score changes. A "B" or "C" zone hit,, the score is 4 points for major, and 3 for minor. A "D" zone hit is worth 2 points for major & 1 point for minor.
The concept of using p/f as a measuring device for USPSA is because a heavier bullet traveling faster has more recoil, while a lighter bullet traveling slower has less recoil. It translates into how fast a competitor can recover from each shot, and be back on target.
Using an extreme example,, compare it to how easy & fast you can shoot a .22 LR as compared to a .44 magnum.
In USPSA,, the way the scores are calculated is your score (points) divided by your time. That gives us a scoring method called "Hit Factor." Let's say a course of fire is designed to where you have 16 targets to be engaged with 2 rounds each. That's 32 rounds required. If all hits are in the "A" zone, the max number of points will be 160. But if competitor A shoots the course in 20.5 seconds,, and competitor B shoots it in 21.5 seconds, the Hit Factor will be higher for competitor A. Competitor A will have a h/f of 7.804, while competitor B will have a h/f of 7.441.
In USPSA,, the game is about combining speed & accuracy to be the winner.
So,, when a given caliber, load & recoil are all combined,, a competitor want something that will allow him to be as fast as possible. Power factor is a way to try & keep the scoring as close to equal as possible.
Most competitors reload,, and they build a load for their gun that meets the criteria for the necessary category. Nowadays,, with a p/f criteria at 165 for making "major" and to be legal, a p/f of 125 is required for "minor." So a reloader will try & build an accurate load where it's just above the threshold to make p/f,, to allow themselves the softer recoil and to be quicker on the recoil recovery for their next shots. In 9mm a shooter may be using a bullet of 147 at a velocity of 850 fps,, and would fail chrono. That makes it's p/f 124.95. but if they build a load with the velocity of 875 fps,, they get a p/f of 128.6. It passes. And using a 1911 in .45 acp,, using a 230 grn bullet at 725 fps,,will get a p/f of 166.7. It'll pass.
But most reloaders build in a small buffer for their ammo,, if it's too close to failing chrono. A .45, 230 grn going at 735 fps will get a p/f of 169.0 pf,, and easily pass chrono. If you shot a 9mm 147 grn bullet at 735 fps, the p/f would get a p/f of 108.0. VERY soft recoil & has a p/f difference of 61 points.
Now that I've detailed the how's & why's of it,, let's look at what actually happens.
By shooting a larger caliber even at slow speeds you get a higher p/f than a smaller lighter bullet going faster. The physics translate into energy & that's where recoil is at. That, and downrange,, a bullet going very slow is not as effective as one going faster in general.
In SASS competition,, they do not use p/f and you can see some REALLY light loads used. You can watch a bullet fly to the target.
I have watched a guy shooting .45 Colts,, with his stated velocity of "about 500 fps" and his bullets barely dinged the steel.
Power factor boils down to a more simple way of measuring energy when shooting. And it's a great way for the casual shooter to figure out a good load they can shoot AND be effective for what their intended use is.
The explanations above delve into most of it,, and even truly point to the more technical info. All very good info for those unfamiliar with it.
As a long time USPSA competitor,, who prior to 1998 had very little knowledge of it as well, I got introduced to it's use. It is used in real gun competitions as a way of trying to level the playing field for competition. It's not a computer game thing,, it is real world.
When I started in 1998,, I discovered that USPSA had a way of "measuring" felt recoil by using what is known as power factor. The basic formula is "Bullet weight, X velocity, divided by 1000." And USPSA had what is known as "Major" & "Minor" power factor (p/f). It used to be,, for competition, the dividing line was a p/f of 175. Many years ago,, for the USPSA game,, it was reduced to 165.
When I started in USPSA,, I was using a 1911 in .45 acp. The most common bullet is a 230 grn round nose. Factory ammo usually chrono's at about 850-925 fps depending upon the maker. Using that, let's look at a factory p/f. Using a 230 grn bullet & the velocity of 850, we get; 230 x 850 =195500. Divide that number by 1000, and you get a p/f of 195.5. Or 20.5 points above the threshold required to make "Major." In USPSA,, the SCORING on a target is divided into different levels of points depending upon where you hit a target. No matter what p/f you are shooting,, a hit in the "A" zone gives you 5 points. BUT,, outside the "A" zone the score changes. A "B" or "C" zone hit,, the score is 4 points for major, and 3 for minor. A "D" zone hit is worth 2 points for major & 1 point for minor.
The concept of using p/f as a measuring device for USPSA is because a heavier bullet traveling faster has more recoil, while a lighter bullet traveling slower has less recoil. It translates into how fast a competitor can recover from each shot, and be back on target.
Using an extreme example,, compare it to how easy & fast you can shoot a .22 LR as compared to a .44 magnum.
In USPSA,, the way the scores are calculated is your score (points) divided by your time. That gives us a scoring method called "Hit Factor." Let's say a course of fire is designed to where you have 16 targets to be engaged with 2 rounds each. That's 32 rounds required. If all hits are in the "A" zone, the max number of points will be 160. But if competitor A shoots the course in 20.5 seconds,, and competitor B shoots it in 21.5 seconds, the Hit Factor will be higher for competitor A. Competitor A will have a h/f of 7.804, while competitor B will have a h/f of 7.441.
In USPSA,, the game is about combining speed & accuracy to be the winner.
So,, when a given caliber, load & recoil are all combined,, a competitor want something that will allow him to be as fast as possible. Power factor is a way to try & keep the scoring as close to equal as possible.
Most competitors reload,, and they build a load for their gun that meets the criteria for the necessary category. Nowadays,, with a p/f criteria at 165 for making "major" and to be legal, a p/f of 125 is required for "minor." So a reloader will try & build an accurate load where it's just above the threshold to make p/f,, to allow themselves the softer recoil and to be quicker on the recoil recovery for their next shots. In 9mm a shooter may be using a bullet of 147 at a velocity of 850 fps,, and would fail chrono. That makes it's p/f 124.95. but if they build a load with the velocity of 875 fps,, they get a p/f of 128.6. It passes. And using a 1911 in .45 acp,, using a 230 grn bullet at 725 fps,,will get a p/f of 166.7. It'll pass.
But most reloaders build in a small buffer for their ammo,, if it's too close to failing chrono. A .45, 230 grn going at 735 fps will get a p/f of 169.0 pf,, and easily pass chrono. If you shot a 9mm 147 grn bullet at 735 fps, the p/f would get a p/f of 108.0. VERY soft recoil & has a p/f difference of 61 points.
Now that I've detailed the how's & why's of it,, let's look at what actually happens.
By shooting a larger caliber even at slow speeds you get a higher p/f than a smaller lighter bullet going faster. The physics translate into energy & that's where recoil is at. That, and downrange,, a bullet going very slow is not as effective as one going faster in general.
In SASS competition,, they do not use p/f and you can see some REALLY light loads used. You can watch a bullet fly to the target.
I have watched a guy shooting .45 Colts,, with his stated velocity of "about 500 fps" and his bullets barely dinged the steel.
Power factor boils down to a more simple way of measuring energy when shooting. And it's a great way for the casual shooter to figure out a good load they can shoot AND be effective for what their intended use is.
It's sort of a difficulty factor. Controlling a minor is easier than a major. Minor rounds are usually smaller giving a capacity advantage as well. A 9mm will usually hold more than a 45 and recoil less. Also a hit with a major can generally be considered more effective.
vlavalle
Single-Sixer
Well, this sounds like this term is used solely in some sort of competitive shooting and contests then? I fully agree that shooting the much smaller, and lighter rounds would be a lot easier. But I also question this measurement, especially when you tell me that it has been around for at least 50 years. The reason why I question it, is not that I doubt its validity, but that it is not mentioned anywhere - not by any ammo or gun manufacturer, nor online with any of the gun/shooting videos, and I have watched a lot of them. Of course, there may be some references somewhere online, and that there may be a world that uses this term and measuring method, but it does not seem to have any real significance.
But I am not against this factor's attempt to try to equalize to some degree the huge differences in power, kick, and effort it takes to shoot the various calibers and loads thereof. I read a lot about how the 9mm is so great, and that you can even go hunting with it, and when hunting larger game (not real large game), it is still effective. But it really is a pea shooter, and the average power (in ft lbs.) is only 350 ft. lbs., and this caliber is constantly compared to the .45 ACP, which is NOT a pea shooter at all. So, when using this Power Factor, it shows this huge difference between the 9mm and the .45 ACP because it is not relying on the speed factor so much as the ft. lb. measuring technique does. The 'average' .45 ACP round is around 425 ft. lbs., which doesn't look as if there is so much difference.
vlavalle
Single-Sixer
Great comment 41Dude! Thanks.
There is also this one...
thebiggamehuntingblog.com
What Is The Taylor KO Factor?
A description of Taylor KO Factor, a method for comparing the relative stopping power of big game hunting cartridges developed by the legendary John Taylor.
thebiggamehuntingblog.com
GasGuzzler
Hunter
.357 will follow.
Also sir, prior to 1972 cars rated in GROSS HP,starting in 72 thier rated like now,Net HP...That 360 HP was gross HP..MINUS about 20 percent to get net HP..SO that 360 HP wud be bout 285-290 in Net HP..
If you look at REAL 10MM loadings, like Underwood ammo,yull find it meets or exceeds a 357 in SAME legnth barrel..Many mainstream makers load 10MM in the FBI loading..No bias here,got Gaggle old Smith 357s, and couple 10s..Ruger offering SUPERVREDHAWK in 10mm now..Gotta be strong for ruger to make SUPER REDHAWK in a 10..None for a 357..GPv100 or backhawk for 357..I got both..That 6 inch BH in 357 SPOOKY accurate..Love em both,but in 180-220 grain,the 10 has it over 357 in same barrels..Check Underwoods Data, matches my Chrony readings..Glock 20,.Lone wolf fully supported ported barrel, 22bLb recoil spring..
Thanx for the time
,CraigAlso..I too lived thru that era."No replacement for displacement"
Your right bout Stang..We didn look at it like a GTX or a Goat..90% were slow, 289s most common, slow, and 302s were ALL 2 barrels FROM FACTORY..EXCEPT A REAL 69 or 70 Boss,solid lifter.. but those RARE..Still,even that motor,not much low end torque..ONLY the scarse 428 FE -CJ ,,OR 429 CJ, OR ULTRA RARE Cammer 429 could run like a common 440HP..80% WERE common 289..even the 271HP version got EATEN by even bigger cars, 428GrandvPrix..or 454 Monte..GREAT MEMORIES!
I have two .44 magnums now, and one .44 Spcl. When I shoot, I mainly shoot the .44 spcl, cause it is my woods bumming, around the ranch gun. I do reload straight walled cartridges. The other gun I shoot is my LCP MAX in .380, as it is my go to town defense gun. It really conceals well, but has enough ammo to let me take care of business.
gramps
gramps
…whatchu talking about Willis ??
Back in the day as for the true muscle the 64 GTO was the original muscle car. I ran Mustangs all my life
pretty much in high school and still today i've got a original Boss 302 W code 430 dragpak sitting in the garage next to an all original
94 lightning. I ran every weekend on a road call telegraph in dearborn Mi and the down river area. Back then i had a 70 Mach 428 SCJ 4 sp and i'd take on those hemi cars and chevy and smoke them. So don't tell me that Mustangs weren't muscles cars!
pretty much in high school and still today i've got a original Boss 302 W code 430 dragpak sitting in the garage next to an all original
94 lightning. I ran every weekend on a road call telegraph in dearborn Mi and the down river area. Back then i had a 70 Mach 428 SCJ 4 sp and i'd take on those hemi cars and chevy and smoke them. So don't tell me that Mustangs weren't muscles cars!
