View Full Version : Major re-think?

The Scandinavian
January 15, 1999, 04:32 AM
Does anyone else think that the time could be ripe for a re-think of how IPSC major and minor power factors are calculated?

I was wondering about using a true 'power' based measurement rather than the current momentum based calulation. At present, the awesome .224 BOZ (say 50gr @ 2000fps) doesn't even make 'minor', but a bowling ball only has to be rolling slightly across the floor to make 'major' easily. So there: A projectile that's too low pf to make minor will penetrate all kinds of armour, and still be lethal, and yet another projectile with a massive pf won't even bruise your foot if it hits you.

So much for IPSC Power factor then.

On a more practical level of course it means that you can have 40 loads that don't make major and yet have way more true power (measured say in Ft.Lbs) than some 45 loads that make major easily.
The reason for this apparent discrepancy is that the kinetic (movement) energy of a projectile is in fact proportional to mass times the square of the velocity, and not as IPSC measures it, simply the mass times velocity.
This leads to a system that disproportionally favours heavy bullets, and (to cut what is becoming a long story short) could lead those using say 40's, or 9mm's in open class, to push what could be already, in true power terms, comparible to the 45, past sensible limits.

In conclusion, is there any feeling out there in favour of a muzzle-energy based
power factor: A true power factor?
<font color=red>T.S.</font>

[This message has been edited by The Scandinavian (edited 01-15-99).]

January 15, 1999, 10:33 AM
The PF thang based on momentum is good for computing pool ball collisions
but not naming potent of projectiles.

If U remember from yer times at Uni, the amount of spent energy on collision is the amount of work that reforms the bodies participating in a collision.
And finally ends up heat, due to the internal friction, between the structural particles of the worked materia, that resists the change of their formation.

Thus energy (or rather the amount of it spent to reform the target) should be the measure of the "practical" efectivity of the projectile used in such matches that need PF evaluation.

Michael Carlin
January 15, 1999, 11:49 AM
We have the PF due to the personal prejudices of the pioneers of practical shooting. Jeff Cooper and others felt that energy was irrelevant, that "momentum" was more accurate of "stopping power".

Who dares to argue with these gurus is shouted down in a cacophony of attacks on "eggheaded physicists"!

But a rule must draw an arbitrary line somewhere and so we have the PF rule. It is simple to compute, and easily measured.

(So is the Army Physical Fitness Test)

Neither the APFT nor the PF reflect the true capability for performance of the assigned task(s).

Just my $.02 worth!

Ni ellegimit carborundum esse!

Yours In Marksmanship


Dan C
January 15, 1999, 03:58 PM
Okay, here is another engineering geek putting in his $.02 worth. The power factor is based on momentum for two reasons: it was an easier calculation using the ballistic pendulum and (2) the forefathers of IPSC wanted to make sure that the "wimpy" 9mm would not be considered a "man's gun".

As far as changing the power factor goes, yes, I am all for it. The one problem I see is all the folks out there who shoot 45 acp. That gun is set up to shoot a heavy projectile at low velocity. I am not sure it can be downloaded to a pf around 150 or so. I do not have much experience with 45.

It was mentioned on another board that instead of lowering the power factor, we raise it instead. That way, the people who would benifit would be the folks who are shooting hot loads and choose to do so. The recoil they would have to deal with would be the price they would have to pay for scoring major.

January 15, 1999, 06:40 PM
I think the question is why ? It's worked well since it's inception, around here the cry for lower pf seems to be led by guys shooting .40s who are having problems. Do we all want to end up shooting steel guns- wimp loads, 6 lb recoil springs ? I don't think so..

Dan C
January 15, 1999, 07:53 PM
Well, you are correct in guessing that I am a 40 shooter. I like shooting minor, and do so every once in awhile. I would like to see 9mm be a viable load for IPSC, not for any reason other than they are fun to shoot and it might bring in more people. I am not into the "P" aspect.

Michael Carlin
January 16, 1999, 12:09 AM
In terms of practicality, the 9mm seems, at least in the eyes of some, to have caught the .45 as a stopping round. So maybe the prejudices against the 9mm should fall.

From my point of view the PF rule is fine, as long as we do not get confused about its relationship with practical effectiveness.

Raising the barrier is attractive, as I have always exceeded the PF by a fair margin.

I suggest that were we to change it we ought to look at a minimum diameter of 9mm and a major level of say 500 foots pounds ( :) )
YAH! DA 10 be da ONE

Seriously, the fact that the level was set up in such a way as to favor the big slow bullet over the lighter faster bullet is a reflection of a preconcieved notion. But I am not sure that chanign it now would be in the best interests of the sport!

Ni ellegimit carborundum esse!

Yours In Marksmanship


[This message has been edited by Michael Carlin (edited 01-16-99).]

Dan C
January 16, 1999, 01:05 AM
I guess I fail to see what would be the downside of having the 9mm be a legit cartridge.

January 16, 1999, 02:19 PM
Dan, the 9 is a legit cartridge- for minor scoring. The idea isn't just that a major gun is a manly gun, a gun shooting major loads is more difficult to master than one that shoots minor loads, hence the scoring difference.An acquaintance of mine won one of our sections larger local matches, limited division, two weeks ago, shooting a minor gun. No, he's not a GM, just an A shooter that pretty much shot all A's. DVC.

Dan C
January 17, 1999, 01:46 AM
Motorep - I understand your point, and that is why I am interested in raising the power factor. The folks who want to shoot full power ammo can, and would be rewarded. Those of us who choose to shoot minor can do so. I do not think it is fair to select a "major" level based on 230gr 45 acp. Times have changed. Amunition has changed. I feel that it is time for the power factor to change or be calculated differently. Is it easier to shoot 125gr .357 magnum loads or 230gr 45acp?

The Scandinavian
January 17, 1999, 03:58 AM
Hi again, no, I'm not calling for a lowering of the PF, just calculating it an a different way. As I pointed out in my first post, sometimes really powerful loads don't make major - and the reason is simply that the way IPSC calculates what's powerful and what's not is wrong. So why not change it?

January 17, 1999, 04:04 AM
Scandinavian has it just right.
Check the IPSC rules 13th ed.
Rule 2.03 DVC:

Accuracy, power and speed. Thats right - power. Not momentum

January 17, 1999, 10:20 AM
So what would you raise it to? 180? We're there already. 185? That's starting to push it, don't you think? That'll make most go for 190, just to make sure, and there are still those guys that don't have a chrono that will realy bump it, just to make sure...

January 17, 1999, 10:35 PM
Ahem... this talk about 9mm(Para) I presume, not being a major calibre confuses me remarkably. 9X19, 9X21 and .38Super ARE major calibres. It's just this 4/10" rule in stock class that makes them "minor".
It only takes a racegun with heavy enough barrel and free bore in front of the forcing cone. Col at max. that will fit in to the mag. that usually being around 29.8 m/m in 9X19 weapons. and some high density slowish powder such as 3N37 or N105SuperMag. and á voilà U're there. Naturally if one isn't interested in occupying the wonderous world of airborne fingernails/fingers/other components of hands, the use of unjacketed heavyish projectiles is strongly recommended.

What bugs me in the present situation of stock class ruling is that in order to be competetive one needs a .40S&W gun that takes 16-17 rounds, and ammo that has been loaded with minimal amount fastest powder that the case/barrel combination possibly can take in order to minimize recoil and still make major.
This isn't too healthy a situation since the guns and the brass are remarkably stressed because of the effort of pushing heavy bullets like 180grainers to major velocity and having such a small combustion space behind the projectile.
This is fine by serious racegunners that have sponsors and so on but what I liked to see is a situation whereas an average clubman could shoot fairly competetively without fear of having his index finger on low earth orbit due to a microscopic change in new powder batch or wrong phase of the moon ;)
As the stock class is supposed to be somewhat opposite phenomenon to Open class an availability to load brass, say 15 times or untill the primers start fall of their pockets would be compliant with the guidelines of the class.

Naturally the energy method of PF evaluation would be the most sensible or atleast "scientific" method but whatever the method is the limits should be set so that the "reasonability challenged" persons wouldn't be encouraged to push safety limits in their loadings and create bad public image of sport that one has a fairly good chance of noticing that the guy next to you has his mag stickin' ot of his foot and his index finger has found a new home in yer ear. ;)

Of this "super major limit" discussion I've noticed that when U shoot an ipsc 'popper with softpoint bullet and the hit forms a bulge to back surface of the 'popper and the front end of the 'Popper's base hops slightly off the ground when the moving part slams down that fits my idea of "super major" :) So far .45winMag and .50AE, latter with maximal load, have got the job done.
I don't know of the PF must be around 400 or so. I think that such a recoil should be compensated by remarkably higher scoring if one insist of using the biggest, baddest and machoest handgun available :)
Differrence of 10 or 20 in Pf isn't after all so remarkable in felt recoil.

Anyhow I suppose that the conversation on this subject will go on which is a good thing IMHO.

Gatt = ;)

January 18, 1999, 10:12 AM
OK How's about this for a suggestion?

Minor: 9mm/0.355" minimum caliber
340ft/lbs minimum power

Major: 10mm/0.40" minimum caliber
400ft/lbs minimum power

These figures are just suggestions off the top of my head for debating purposes.

We have to remember that the weapons have changed from the days of single stack seven round 45's in major versus fourteen/ fifteen round 'wondernines'. The point is that then there was a real difference to make up for the inequality in the scoring - it's just not so any more. Times have changed, the guns have changed, and now the rules need to change to catch up. Better late than never?

Ray VanderLinden
January 23, 1999, 08:27 AM
I fail to see the problem here. If you want to shoot light recoil loads then accept minor. If you are willing to shoot harder recoil loads shoot major.
My 200 grain .45's make over 200,000, why? The word everyone forgot PRACTIAL. My duty loads are 200 gr Gold Dot +Ps, I load all my practice loads, or compitetion loads, to the same or nearly the same velocity. I shoot a single stack 1911, no comp, no optics. Yes a small fast bullet will shoot through armor, so will the old .30 Mauser, it is a dismal stopper though. In the real world the 9mm with good hollow points works good, if the hollow point doesn't get plugged, the .40 has shown it's self to be a good stopper. The idea of power factor can be changed all you want and it won't change a thing. SOMEONE will still be unhappy. If you take the arguement I hear in this string to it's Illogical extreme the next thing I'll hear is that, that new super .22 is better for hunting elephant that the 458 Win Mag. Minor gets less points Because it's easier to hit fast with. Major gets no more point than Minor if you hit the A zone. In the world that IPSC was meant to train for bigger bullets do more damage than little bullets, ie. they let more cold air in and more warm blood out.
If all it is to you is a game, then play by the rules you knew were in place when you started, and stop whining.
If you use the "Game" to add some fun to Training, then shoot what you carry and you only have to compete against yourself.

January 23, 1999, 08:40 AM
Good points!! Haven't shot IPSC in just over a year due to extenuating circumstances but was using a single stack 1911 with just over a 200 PF. The other shooters couldn't understand why I was shooting that "heavy" of a load and kept suggesting I lighten up my loads to about a 180. Kept having to explain why I liked my load. Hopefully will be getting back into IPSC this year and thinking of getting into IDPA also.

January 25, 1999, 02:16 AM
1. Yes everyone has the same rules so it's just as fair or unfair for everybody.

2. Yes it's right to reward those using higher power ammunition, and it's in the rules too.

3. What's illogical is measuring momentum and saying that's what power is. The IPSC power factor measures momentum NOT power. That's as illogical as measuring time in degrees Farenheit.

4. Suppose I want to leave my 230 grain 760fps 'Major' .45 at home this time and shoot something more than 60% more powerful instead - OK? Lets bring along my .40 with Cor-bon 135 grain loads, at a realistic 1270 fps or so. DO I GET REWARDED FOR SHOOTING THIS NEARLY 500 FT LB LOAD? No, if anything I get penalised because now I'm shooting minor. That's illogical.

5. I think that's just about as clear as it gets, but for those that still don't get it look in just about any elementary physics textbook under "equations of motion".

Ray VanderLinden
January 25, 1999, 06:11 AM
In the books I've read, a Foot Pound is the amount of energy required to move one pound, one foot against the force of gravity. That sounds very close to the transfer of momentum to me.
If you can show me that your 500 foot pound load will move a 1 pound chunk of steel even 3 hundred feet into the air then the foot pound arguement will be valid.
One time when I had way to much time on my hands, I figured what the foot pounds of a neutron at the speed of light would be. I can't remember the exact number, but one has more foot pounds than the wieght of a sky scrapper. Yet the earth and even sky scrappers get hit by them everyday, where is the damage?
To bring it to earth a little more, a 500 foot pound load should, according to physics, knock a small elk down even if it didn't kill it, so long as the bullet stopped in the body (expended all it's energy). That isn't easy to do even with a 2000 foot pound rifle load.
Foot pounds are great on paper, but it doesn't work in the real world.
BYW boost your load a couple tenths and I bet it'll make Major. 1300 fps does. : -)
[This message has been edited by Raymond VanDerLinden (edited 01-25-99).]

[This message has been edited by Raymond VanDerLinden (edited 01-25-99).]

January 25, 1999, 11:47 AM
I think the elk shouldn't fall over.
Medium size female elk should be about 500Lbs, or 3500000 grains.
Momentum IS what we use to calculate this so
(135x1270)/3500000 = 0.04
so Elk moves away from the collision at 0.04fps, not nearly enough to make it fall over.

Egghead note - yes I do know that for a perfectly inelastic collision the formula is
m1v1 + m2v2 = (m1+m2)V
but as the mass of the bullet is such a small fraction of that of the elk...

[This message has been edited by 003 (edited 01-26-99).]

The Scandinavian
January 26, 1999, 03:23 AM
Hi there again,
I'm pleased that this thread has sparked off an interesting debate.

Raymonds point about the Neutrons was interesting so I decided to do the calculations. Approximately:

Weight of a neutron = 5.14E-23 grains
Speed of light = 9.84E8 fps
so, by mvv/450240 (a good appoximation)
gives us the energy of a neutron as...

wait for it....

1.1E-10 foot pounds. Virtually nothing in other words. Whew! Still it explains why they don't knock chunks off skyscrapers....

Still I accept Raymonds point about stopping power not necessarily being related to muzzle energy. But I can't accept that it's related to recoil either. Who chooses their loads simply because they recoil more? No-one, I expect. I think my original thesis still stands, which was that power for IPSC should be measured by power rather than momentum. 003 care to comment? Raymond? Anyone else?

Thanks as always to everyone for the great debate! T.S.

Ray VanderLinden
January 26, 1999, 03:46 PM
It was a long time ago I did that computation and I may have had something a little larger than a neutron in mind.

Still the problem I have is that those wanting to change the PF All tend to be trying to push the limits. Yes a 230grain bullet at 760 fps will make major. I don't consisder it an honest load in a .45 pistol.

I can agree that the momentum formula gives too much creedance to bullet weight. But the Foot Pounds Formula gives too much creedance to speed also.

In General it can be said that the rounds that cause more recoil tend to be better stoppers if all else is equal. (ie. bullet design)

Also to make the shooters always looking for that little advantage in the GAME, will make the PF rule so complicated that we have to take a computer to the range with us just to figure the PF.
BTW a 135Grain .40 Cor-Bon make 1300 FPS making 507 Foot Pounds and a PF of 175.5. Gee, that sounds like major to me. A 155 grain at 1205 (factory Win) makes 500 Foot pounds. And a PF of 186.8 and probably about the same recoil.

January 28, 1999, 02:13 PM
I think there are 3 major reasons the founders went with the way they calcualte pf and the levels.

1. They did not like hi-cap 9mms. Plain and simple. A real man shot a 1911 in .45.

2. They wanted to keep the calculation simple. Some of the folks who posted on this thread understand dynamics, other obviously do not. Energy, Power, Work are all dynamic terms related to each other. Momentum is a simplistic formula that gives us PROPER numbers in some cases. In the real world, momentum is near impossible to find. Dynamic, real physical systems are highly complex with mutiple degrees of freedom, as many as 6. Momentum CAN NOT account for these. Momentum is a starting point in many rigorous engineering problems, but it soon falls by the way side and more powerfull calculations are used.

3. A measure of safety to keep hot-rodders from blowing their guns.

If those were not the reasons, they are now.

Now, the rules are made and maybe we should live by them. But, the rules are in contradiction, they say Power but calculate Momentum. WRONG, minus at least 50% on any test I have ever taken, not just for the wrong number, but for the wrong comprehension and undersdtanding!

I agree that the PF calculation should be altered to reflect true dynamic properties. How this is accomplished is another question.

Who said that the .40 S&W is not proven as a reliable stopper? No disrepect meant, but look at some numbers, have you been in secluson for the past 10 years. Most PDs have or are switching to it and several rounds exceed the best .45 load!

As for ease of calculation, I have shot many mathces and have never had a load chrono'd except at a mjor match where everyone did. The guys keeping score were using calculators and so, really, how hard is it to push 1 more button? How many of you can really calculate (1237*135=pf) in your head? Good thread Scandinavian. Good Shooting, MarkCO

Ray VanderLinden
January 29, 1999, 02:53 PM
Good Observations MarkCO,
Can I calculate PF in my head, No not reliably, I can with pencil and paper though.
easy thing to have at a match, just turn over a score sheet.
As to the .40 being better than the .45, Maybe I haven't seen those states but I'll take your word. Problem all this energy is useless until you take Bullet Design into account. Do we now bring out enough calibrated Balistic Gelatin to the range? And who's standards do we use? Fackler, Sanow, the FBI?
And by the time we test all the bullets for speed weight and Design and get done arguing about what to use as a standard Someone will still have a complaint that you can build, into a reason it's unfair.

Mean while those of use that shoot for training and or Fun will be shaking our heads, but not so hard as to mess up our sight picture as we shoot the COF and enjoy shooting Major and Minor.

PS. I shoot Both, in neither do I shoot the lightest load that makes it. If you want to make money at it then you have to get so good at the Game that the Major/Minor Debate doesn't matter any more. I've never heard Barnhart or the Jet complain.

January 31, 1999, 11:54 PM
The above discussion was not complaining but rather thoughts about the scale on which to measure the potent of projectiles that is supposed to be rewardable in ipsc type competition.
No spesific limits were named, should one insist using biggest,baddest etc. etc. the energy limit can be set at 20KJ(s=0) so that .50BMG won't make it without excessive pressures.
I really can't understand a point that $4 taiwanese calculator is too much if one can't compute the energy in his mind. And why should one ? If the event participated is of any significance there will A) be laptops present for following the the progress of the competition real time and to provide competitors and spectators with the knowledge of their present standings between stages. B) the "PF" calculation is worry of the organising party anyhow.

For matters of simplification it could be assumed that terminal ballistic behavior of all the bullets is equal, thus leavings us only the energy to worry about.

As seems that many insist on animalistically simple analogues: Fairly stiff load of 5.56Nato makes just about major whereas Nato spec. .45acp load makes it easily. Where can be found those persons that rather get shot with the rifle than the pistol ?

The reason why Jet and Burner don't "complain" about PF is most likely divided in two parts, first of all they're professional gamesmen so it's completely irrelevant to them if they were throwing toilet seat covers at the targets as long as they get paid the heaps they do. And secondly burner is former electrician and Jet whatever by education and trade, they simply totally lack the education to understand higly complex dynamics and fysics and thus they most likely haven't give a second thought to the trueness pf evaluation and even if they have the above reason applies, attleast publically.

For example practically none of the Indy/CART drivers can comprehend the complexity of the stress analysis, aerodynamics and uneven gasdynamics involved in creating competetive vehicle for them.

Equally I'm pretty sure that most pros have enough to worry about in their own practise and developement rather than the gun as long as it goes bang, the bullets land where aimed and load/gun meets the rules. (yeah yeah fits hand etc. etc. the usual things)

If the departments of ordnance had been listening to gun "gurus"(=old fat gitts) around the world, the infantry battles would be still fought with "good old rugged and reliable weaponry" like single shot rifles, since "a repeater rifle will only lure troopers to waste their ammo".

At the point when any society involved in any technological interest throws the anchor and refuses to develope since a "guru" says something theres something seriously going wrong.
Analogue to point succesfulness of anti guruism and scientfic aproach is Glock gmbh, what I know Gaston Glock had never fired a weapon before the project. How large percentage of US LEOs use glocks these days?

Even if the "founding fathers of ipsc" had to set the PF evaluation the way it is because of lack of chronys and calculators (and not because of social interest in "Man's guns" and economical connections in modifying such ;). Why should we let that keep us down, at the days that only place one sees a ballistic pendulum is museum.

And finally if energy doesn't work terminally in real world, I'd like too see the dude too that stands next to PF=0 stationary device, derivated from one german jewish egghead fysicist's thoughts shuch as E=mc^2 :)
The lad really isn't hurten when he turns into plasma, since it's only energy and no momentum ended up to him before total disintergration.

"In the future I will understand better"
Gattling = ;)