Why do we use power factor instead of kinetic energy?

[outerlimits]

Perhaps a better example is shooting second chance.

ahhh...man! you're really dating yourself now. first the ballistic pendulum comment and now this....bringing up second chance.

I am assuming you mean the bowling pin shoot.

@ Gforce, it's squaring the velocity in the KE equation that bugs me. as you can see what was posted up above numbers-wise, the 9mm Para puts out more foot-pounds than that .45ACP, hence, therefore, ergo, all police departments and federal law enforcement agencies should be required to carry the more powerful 9mm pistols.

just kidding...

.50AE is "good med'cin" for bowling pins. I've seen it with my own two eyes. I felt it too.

9mm Major is anemic.

.40 at major power factor is better

.45 ACP is next.

and some guys are stuffing a cast lead 255 grain boolit meant for the .45 Long Colt into their ACP cases.

shot placement is critical with pins.

at our pin matches the table is 3 feet deep and the pins are set back a foot and a half from the edge...so you have to knock the pins clear off the table. the timer stops when the last pin falls off the table.

you are partner'ed up with another guy who has 5 pins to clear on his side.

I get to use my laser grips. :-)

when i did second chance, i was loading 285 GR HP with 700/800x. 5 pin tables were 4' x 8', with the pins 1 foot from the front edge. square hit and those things left the table pronto. the 9 pin event was for 9/38 and the pins were only 1 foot from the back edge. patrick can chime in for sure. i never shot the 9 pin.

[Chills1994]

I really, really hate that picture, for a number or reasons. I have an X raTed nickname for that pic.

it is missing data. when I see missing data I slip into "figures lie. and liars figure" mode...or "there's lies, dayum lies, and then there's statistics" mode.

which hollow point? whose hollow point?

what type of gellating.

I am assuming ballisticians have come up with an industry standard as far as percent gellatin at such and such ambient temperature located some odd distance from the muzzle.

were there clothes placed in front of the block of gellatin?

how about drywall?

a car windshield?

and the thing that really irks me the most is that you are given a two dimensional presentation of an event which occurs in four dimensions.

if you don't quite catch my drift there, go to YouTube and type in Barnes bullets at the search window. in the results should be slow motion videos of their bullets being fired into a block of gellatin. it is quite violent.

and as far as I know, I haven't heard about any ballisticians trying to measure or capture that "shock" data.

in a way, it is akin to when Dale Earhardt Sr. was killed in that one NASCAR race. at first blush, the accident didn't look all that bad. but seen in rweal time, the energy transferred to his car was in such a short duration (impulse...err.."work") you could see how that would be so devastating.

[ima45dv8]

This topic was supposed to be about WHY power factor was the chosen measurement system in IPSC/USPSA competitions -- NOT about the terminal performance of various rounds by whatever testing method has been used. Please review the Forum Guidelines for further information.

This one has strayed into that area far enough. No more posts on that subject or they will be deleted and the thread will be locked.

Thanks...

[Erik S.]

I think the reason Mr. Cooper chose to use PF (momentum) instead of kinetic energy can be related back to the concept that shooters must be rewarded equally for both speed an accuracy. Since the difference between shooting major or minor CAN effect speed, a linear relationship was needed to keep it fair across the board. The momentum calculation does just that. PF (momentum) relates to impulse as well (area under the force curve that changes the momentum of an object) (i.e. shooting a gun). Since impulse is esentially the "kick" of the gun, it equally awards those who shoot major or minor, hence the delineation for scoring. Ignition time is perceptively (is that a word?) the same in all handguns.

[Cosmik de Bris]

I think the reason is that momentum drives the recoil not the energy, and it is recoil that affects follow up shots.

[1fng]

Because, in the beginning, chronographs were not common like they are today, for one. Momentum was easy to measure with the pendulum, and there was a definite bias toward the .45. I think mainly because at the time that power factor was developed, the .45 was seen as a significantly better 'combat' cartrige than the 9mm by Col. Cooper et al. If you didn't shoot the 'manly' .45, you were to be penalized. Even if it would have been easy to measure kinetic energy, there was a bias against that, because 9mm would look 'better' compared to the .45. The .45 wins the momentum race handily.

Also, bullet technology was relatively archaic, compared to the bullets of today. Hollowpoints were not anywhere near as efficent as they are now, and more often than not gunsmithing work was required to get those old guns to reliably feed those old hollowpoints. Today, they will reliably expand even when shot through heavy clothes, sheetmetal, gypsum, etc. That was not the case back then. I have read, and would tend to believe, that much of the handgun bullet technology of the last twenty years is directly related to trying to bring the effectiveness of the 9mm up.

[Duane Thomas]

Again we are seguing into discussion of the "effectiveness" of various handgun cartridges. Perhaps that's inevitable in this topic, but it does seem like only a matter of time before I or someone else has to shut this down.

[Duane Thomas]

Before that happens, I will comment that I have discussed the early history of proto-IPSC (before IPSC even existed, back when it was called "combat shooting") with Bruce Gray, who shot his first match back in 1972 at the age of 17. IPSC wasn't even formed until 1976. According to Bruce, in its early years combat pistol shooting was very much a 1911 .45 versus Browning Hi-Power 9mm game. My opinion is that .45 fans, foremost among them of course being Jeff Cooper, developed Major/Minor scoring in order to give their favorite gun/cartridge an insurmountable advantage over the Browning Hi-Power. Otherwise, if hits with either cartridge (9mm or .45) counted the same, the high-capacity Hi-Power would have swiftly become the gun of choice. Couldn't have that.

[shooting for M]

My dad used to tell me about the pendulum, kinda funny. I can't imagine the PF disparity for big matches! From one chrono to another ypu can see a disparity of up to a couple PF points. I couldn't imagine the margine of error. Most of us load at least 5 or 6 above minimum just to be sure for something like that I would go back to running 180 plus! I think the current PF is done cause its easy, speed in how a chrono measures, times weight in how we weigh, no conversions, no real formulas for us less than rocket surgeons out there.

Looking at the ballictics gel pic, kinda funny you never see the load I carry at work, a 155 going about 1300! Gotta love 200PF in a plastic gun!

[Erik S.]

I don't think the discussion of "effectiveness" in this thread is meant to light a fire under the mods. It simply comes down to the fact that the majority of bullet and power tests are done through balistics gellatin, thus producing references to such tests on these boards. Perhaps we should push for a more non-violent method.