Why Won't My Bowling Pins Fall Over ?

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Mike H

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Guys,

I know that this may well re-ignite the .45 vs. 9mm argument, but, can someone educate me on this. When I pin shoot at my local GC with my Taurus PT-99, I can shoot the hottest +P 115 or 124 grain bullets on the market and the lower set of pins will only fall off the target rack onto the floor if I hit them juuuust so, otherwise they just fall over and stay on the rack (not a counting shot in standard pin shoots). There's an old lady two lanes over with her husbands Colt Caveman using lead reloads of around 210gr with what he says is a relatively light load of powder and the pins are actually leaping off the rack and hitting the rubber stop mats in back, one almost bounced back on as I watched ! Now if my Tritons or Corbons have 400 - 500 ft lbs and his .45's have got maybe 350 or less, where is my 12th grade physics going wrong ??

P.S. Got laughed at on my first pin shooting comp recently when I pulled my 9mm out of my range bag.

Help my bruised ego out here.

Regards,

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Mike H
 
Mike - There are several reasons why the 45 is having more success than your 9mm.

As Fred hinted at, maybe your not hitting the pins straight on and she is. I know a real live Annie Oakley and I would never bet against her.

I think the more probable reason is that the 45 is simply transferring more energy to the pin than the 9mm. This could be due to bullet design. Yours may be ricochetting off and hers is digging in with off center hits. The higher speed of the 9mm may be a negative factor and would tend to increase the ricochet effect just as a rock will bounce off water at high speed but goes right in at low speed.

At the range where I shoot BP's. They usually don't pit 9mm's against 45's. For the 9mm sessions, the pins are set a little closer to the rear of the stands. Most shooters have to try to shoot 2 or 3 fallen pins out of 6 pins off the table to win.

That's probably not much help after my 10 yrs of physics. :)
 
The .45ACP has something like 65% more frontal area than a 9mm round plus the .45ACP bullet usually weighs more (in grains) which results in more kenetic energy.
 
Pete80, hit the nail on the head, or in this case the bullet on the pin, sorry.

Any ways two things contribute to the ability of the .45 to kill the pins and the lack of ability of the 9 mm to remove them. Size and Impact Force.

As stated in physics Force = Mass x Acceleration. Thus a 9 mm with a 124 grain bullet (.2834 oz weight) (.008802 oz mass) has a muzzle velocity of 1110 ft/sec, thus impact force = 9.770 lb. x ft/second squared.

A .45 ACP with a 230 grain bullet (.5257 oz weight) (.016326 oz mass) has a muzzle velocity of 835 ft/sec, thus it has an impact force = 13.6326 lb. x ft/second squared.

Unfortunately you forgot to factor in the mass of the bullet. For the record both bullets were FMJ / FMC and unfortunately Remington does not list 210 grain .45 ACP in their ballistic section.

PLEASE WILL SOMEONE ELSE VERIFY MY RESULTS, as I am a human, mistakes are a great possibility.

Hope this answers your question, Mike H.

This is also why a 9 mm will throw a person and the .45 goes right through.

Equations:
bullet in grains / 437.5 = oz weight

oz weight / 32.2 = oz mass

Conversion:
437.5 grains = 1 oz weight (Speer Reloading Manual 7, 1966)

weight = mass x gravitational acceleration (Mechanics for Engineers Statics and Dynamics, Beers and
Johnson, 1987)

gravitational acceleration = 32.2 ft/second squared (Mechanics for Engineers Statics and Dynamics,
Beers and Johnson, 1987)

all velocities from Remington's Web site http://www.remingtom.com/ammo/pages/ammofr.htm


Richard Cizik
richard.cizik.jr@snet.net
 
try this simple experiment--stand and let a 150 pound speed runner,sprinting at full speed, run into you. then do the same with a 250 pound lineman running at slower speed.---the answer may come to you.
 
Gentlemen, I think you're making this more complicated than it needs to be. pete80 is correct that more kinetic energy equals more pin knockdown force. But his error is in neglecting velocity. The 9mm is lighter but faster than the 45. Mike H's assessment of the ft-lbs of energy are very close to what my books say they should be. (Approx. 450 for the 9mm and 350 for the .45.) If you hit the pin with both bullets so that all energy is transferred to the pin, the 9mm will impart more energy and knock it further.

Crij - I'm not sure how you arrived at 9.77 X ft/sec sq. as the impact energy. (This would be a little over 12 million units for the 9mm example given! I'm not sure what the units would be.)

A very useful formula for bullet energy is E (ft-lbs) = v squared/450400 X bullet weight (grains). The factor 450400 takes into account the accel. of gravity and thus the conversion of weight to mass. (The factor will be slightly different for different locations on earth, but is satisfactory for an average.)

addendum for t-wheel - I would rather be hit by the lineman all other things being equal (i.e., he doesn't spear me with his helmet. :) ) If the sprinter is running at 20 mph and the lineman at 10 mph, the sprinter will have over 2000 ft-lbs energy and the lineman will have around 835. This is why more receivers and safeties are knocked out than guards.

[This message has been edited by Mal H (edited October 10, 1999).]
 
Gentlemen,

Thanks for the replies so far, I'm suitably impressed with the application of Newtonian physics, and yet the reply that gets my attention is the least complicated. Namely, the use of LRN's as opposed to FMJ's or JHP's, the lead will deform well and ricochet less, it's therefore more likely to effectively impart it's energy to the pin. Federal make a +P coated LHP, the Nyclad, it's about as near to plain LRN as I can think of for my 9mm. Although this is proving to be an expensive experiment I'm going to try those next before I resign myself to shooting a single action drainpipe, no offense you .45 'ers.

Regards,

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Mike H
 
Sorry, I'm very new to this whole thing, but if it were me, I would have thought to look at the bullet shape, too?

As Mike H mentioned, doesn't the 9mm (even in JHP) have a really sharp, conical appearance, whereas .45 (especially the "Flying Ashtray" load) have a much flatter nose? (However, since I've never seen a lead reload, I have no clue what the front of it would look like.)

Couldn't the 9mm load be glancing off the front of the pins more than the .45's flat front?

Why not go admire her technique and ask if you can try out a carefully aimed .45. ;) At my range, people are more than welcome to show off their toys. That would answer the question of calibre vs. skill...

-Jon
 
Why the pins will not fall over with the fast little 9 but fly off the table with the slow .45?

Let us say there is a vault door standing open and you have to close it. You have two choices fast and slow. For fast, you stand on the far side of the room and run like hell until you run into the vault door. The door will not move much, you will stop and transfer all the energy that is generated from your mass and velocity. Still the door is not going to move very far.

For slow, you walk up to the door and lean against it until it moves. Less energy transfered because of the slower push but the door closes.

Dwell time has to have a bunch to do with the question.

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Ne Conjuge Nobiscum
"If there be treachery, let there be jehad!"
 
Hello, all. The reason the nine is not doing so well on bowling pins is due to its lack of MOMENTUM compared to the .45! While kinetic energy and thus, momentum, can be written in terms of the other, they are not the same thing. Kinetic energy = 1/2 mass X velocity squared. It becomes obvious how the nine's higher velocity gives it more kinetic energy than expected. Momentum can be thought of as the "shove" the bullet imparts. Momentum is
simply mass X velocity. It is clear that 1 gr of bullet is equal to 1 ft/sec of velocity. So, just multiply 800 x 230 vs 115 x 1100. The nine's numbers will be around 4/9 of the forty-fives or about half the momentum. Some of the hotter nines hit around 70% of the standard forty-five ball round's momentum, but the nine cannot match it. These figures are not actually momentum figures as the bullet's weights are not divided by the acceleration due to gravity, but the ratios are the same. Yes, kinetic energy does apply, but the biggest factor in this business of bowling pins being knocked over is momentum. The angle of incidence as well as if the collision is elastic or inelastic also applies. All of this said, my favorite handgun remains a Browning 9mm HP. I think of "kinetic energy" in terms of tissue distruction, and momentum as the "shove." Perhaps this is of use. Best.
 
I noticed the same thing when a 40 S&W is compared to the 9mm. We were shooting smgs and hits from my 40 cal MP5 knocked down pins/plates faster than everybody else's 9mm. Too bad there wasn't a Thompson to compare the 40 with.

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Vigilantibus et non dormientibus jura subveniunt
 
Sorry Stephen, I didn't see your post until now. You are right. Of course it's momentum. (Picture me doing a palm slap on my forehead.) I was hung up on the kinetic energy. When you solve for the force required to stop the 230@850 vs the 124@1200 over a very short period of time, the 230 will win big time. Thanks for clearing it up.
 
I've never shot a bowling pin, but in reading all this, I kept wondering about one thing. Does the 9 go through the pin? It's smaller and faster, so it could quite conceivable be going through the pin, right? If that is happening, then it is not transfering all of it's engery. I've notcied that some things I shoot with a .22 rifle fly all over the place, but a 9 will merely knock it over or something. I just assumed (ass-u-me) that it was cause the .22 impart more energy, but the 9 was just going straight through it.
 
No, a 9mm will not pass thru the pin if hit squarely. Almost every type of bullet stops within 1 or 2 inches with the possible exception of a 45-70. We performed an autopsy on a BP at our last TFL-Mid Atlantic Shootfest and the only ones we couldn't find were the 45-70's. BP's are usually made of rock maple with a very tough shell (cryolac?).
 
well i know that a BP smacked with a 150 gr. 30-06 fmj will sometimes just "fallover" as oppossed to being hit with a soft point or bronze point bullet.. which will filp it into the air. The WAY in which the enegry is tranferred (say in a greater surface area as the bullet expands/disintegrates) seems to make a difference.

BTW MY "bowling pin gun" is a colt 1917 army revolver in .45 acp filled with 200 gr. semi wadcutters and 5 grains of red dot. It always gets a lot of looks when i pull it out of the rug ;) especially by the guy next to me with a para ord. p-16 (lol I usually outshoot that guy) Hold the front sight in line with what you want to hit and squeeze, just like zapping tin cans with a .22.

Dr.Rob
 
All this talk about engineering and physics makes me hungry... At the risk of sounding indelicate... "So that means the 45 is better, right?"

LOL, hold the flames, I've heartburn already!

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Remember: When you attempt to rationalize two inconsistent positions, you risk drowning as your own sewage backs up... Yankee Doodle
 
A few pointers on the topic-

When shooting bowling pins with a 9mm at the range, I have found that if I switch to 124 grain LRN or to a 147 grain hollow-point load, the pins fall much more often and react more violently. The heavier bullets that either expand or deform do a better job of transferring their momentum to the heavy pins.

On another note, the classic F=MA formula cannot be used to calculate the force generated by a bullet on impact, so ignore whoever did that bit of bad math earlier (I studied Mechanical Engineering, University of Florida). F=MA tells you only the required force to accelerate a given mass at a given rate. On moving objects, the only two concerns are Momentum and Kinetic Energy.

Kinteic energy is Mass times the velocity squared. Momentum is mass times velocity. For pin shooting, momentum is the big factor.

According to Newton, momentum is neither lost or gained in a *perfect* reaction. Let's do some math, assuming a bolwing pin weighs 5 pounds or 35000 grains.

115g grains X 1150 ft/s = 35000 grains X Velocity of the pin after impact

which means that in a perfect world, the pin will be going 3.78 ft/s after the impact after shooting it with a 115gr 9mm load.

Now, lets do this again for a .45ACP load.

230 grains X 900 ft/s = 35000 grains X Velocity of the pin after impact

which means in a perfect world, the velocity of the pin after impact is about 5.91 ft/s.

Now, no reaction is ever perfect. Obviously a round that ricochets or goes through the pin does not transfer all of its momentum. Rounds that "stick" in the target or "dump" more momentum into their target will do a better job of transferring momentum. Logically, a bigger, heavier bullet would do a better job of this in a hard wooden pin. In humans, which are mostly water, this may be a completely different story!

Summary: If you shoot pins with a 9mm, try 147 grain LRN of JHP loads.
 
Thanks for the answers, I'll "go heavy" with 147 gr's. BTW my hottest 9 doesn't penetrate our pins at all unless it's one where the plastic outer has already cracked, kinda makes me think about the whole stopping power debate when I see a brand new pin that has almost been blown in 2 pieces by a .308 Win at 100 yards.

Regards,

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Mike H
 
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