115 vs 125 vs 135 vs 145 for steel

[rustychev]

assuming they all are at 130 PF dose bullet weight make a difference when shooting poppers.

[eric4069]

yes, in my esperience 147s knock down steel better than 115 at similar power factor.

Eric

[Sarge]

There are several threads on this already. Very interesting discussions too! some guys go al "scientific" in their opinions while others just tried several and concluded what worked best for them.

Bottom line is, steel is required to be adjusted to fall when hit with any PF LEGAL load so to me it technically doesn't matter enough to make a bullet decision based off of performance on steel alone.

[Hi-Power Jack]

Has anybody posted results of an actual experiment, where the

identical steel is hit by 115, 124 and 147 gr bullets at exactly

PF130?

Or, are all the old posts speculation and theory?

[techj]

If they're all at the same power factor and have the same bullet profile (i.e. RN) they should all work the same as the energy they're delivering is the same.

[Hi-Power Jack]

Apparently there are different types of energy, e.g. kinetic.

[Sarge]

Has anybody posted results of an actual experiment, where the

identical steel is hit by 115, 124 and 147 gr bullets at exactly

PF130?

Or, are all the old posts speculation and theory?

Some of the stuff I read bordered on quantum physics!

[Gooldylocks]

If they're all at the same power factor and have the same bullet profile (i.e. RN) they should all work the same as the energy they're delivering is the same.

Not true, as far as the energy being the same. Velocity is more important in the energy equation. Power factor is a measure of momentum, not energy.

[Hi-Power Jack]

Here we go ... again.

Anyone actually test this ... ?

[ChemistShooter]

Speaking as somebody who has never even been to a Steel match . . .

Did some quick Excel calculation.

At equal power factor, the smaller bullets will have a significantly greater impact energy and will knock the targets over better---IF:

All bullets hit in EXACTLY the same place and at EXACTLY the same angle. it's going to depend on how the plates are constructed. The lever principle will play a big part. The farther away the bullet impacts from the point of attachment, the less impact energy will be required to knock the target over.

[Gooldylocks]

Speaking as somebody who has never even been to a Steel match . . .

Did some quick Excel calculation.

At equal power factor, the smaller bullets will have a significantly greater impact energy and will knock the targets over better---IF:

All bullets hit in EXACTLY the same place and at EXACTLY the same angle. it's going to depend on how the plates are constructed. The lever principle will play a big part. The farther away the bullet impacts from the point of attachment, the less impact energy will be required to knock the target over.

Yet again, I don't think this is true either, necessarily. Because you have to consider the area that the impact is happening over, the different deformation patterns of the bullets, the period of the impact.. higher velocity (energy) projectiles often explode into tiny little pieces when they impact a hard surface, but a slower bullet might not. Elastic collisions transfer more energy right, so I don't know which would actually be better. This is a question for someone much smarter than I.

[peterthefish]

Speaking as somebody who has never even been to a Steel match . . .

Did some quick Excel calculation.

At equal power factor, the smaller bullets will have a significantly greater impact energy and will knock the targets over better---IF:

All bullets hit in EXACTLY the same place and at EXACTLY the same angle. it's going to depend on how the plates are constructed. The lever principle will play a big part. The farther away the bullet impacts from the point of attachment, the less impact energy will be required to knock the target over.

As the prior poster noted, this is incorrect. Kinetic energy is not conserved in the collision between the plate and the bullet because the collision is not perfectly elastic. Momentum is the relevant measure here and is conserved in the collision. Whichever bullet has less momentum after the impact with the plate will have transferred more momentum and will do a better job knocking the plate over.

I'd guess if you threw an 8oz beanbag at a plate at 125 PF (35 mph) it would drop where it hit (all momentum to the plate). Heavier bullets tend to come back much slower than lighter bullets, so anecdotally heavier objects transfer momentum better and are better for plates.

Every time this thread comes up I get an urge to build a ballistic pendulum with a marker to measure max height and at least bring some data to the discussion.

[rustychev]

WOW I guess I will just stick with 125s and not worry about it.

[Sarge]

WOW I guess I will just stick with 125s and not worry about it.

If you load to 132+ PF the steel will fall if you do your part AND the setup crew does theirs!

[Gooldylocks]

WOW I guess I will just stick with 125s and not worry about it.

If you load to 132+ PF the steel will fall if you do your part AND the setup crew does theirs!

+1

[Hi-Power Jack]

WOW I guess I will just stick with 125s

Aren't you sorry you asked ...

[rustychev]

Sort of ya

Sent from my C6750 using Tapatalk

[Kletus]

The bigger, heavier bullet should transfer more energy to the plate in the form work (moving the plate). The smaller bullet may have more energy, but it is going to lose a lot more in the form of sound, deflection, deformation/fragmentation, etc.

Go with the heaviest bullet your gun shoots reliably and accurately.

Do a search for bowling pin loads.... almost every one you find will be for big heavy loads at 210 PF or above. Heavy bullets deflect less... so they transfer more energy.

[Targetpractice]

The bigger, heavier bullet should transfer more energy to the plate in the form work (moving the plate). The smaller bullet may have more energy, but it is going to lose a lot more in the form of sound, deflection, deformation/fragmentation, etc.

Go with the heaviest bullet your gun shoots reliably and accurately.

Do a search for bowling pin loads.... almost every one you find will be for big heavy loads at 210 PF or above. Heavy bullets deflect less... so they transfer more energy.

can't really compare what people are using to knock bowling pins over. They use heavier slower moving bullets to stop it penetrating so much. Steel you don't have to worry about that.

[Kletus]

The bigger, heavier bullet should transfer more energy to the plate in the form work (moving the plate). The smaller bullet may have more energy, but it is going to lose a lot more in the form of sound, deflection, deformation/fragmentation, etc.

Go with the heaviest bullet your gun shoots reliably and accurately.

Do a search for bowling pin loads.... almost every one you find will be for big heavy loads at 210 PF or above. Heavy bullets deflect less... so they transfer more energy.

can't really compare what people are using to knock bowling pins over. They use heavier slower moving bullets to stop it penetrating so much. Steel you don't have to worry about that.

I would argue that they use them to make sure that the bowling pin gets knocked off the table on an off center hit. Heavier bullets will deflect less on a glancing blow. Yes... you CAN run into penetration issues with lighter, faster bullets on bowling pins, but that isn't the major advantage of the big bullets.

Any weight of 9mm will work fine if loaded to the correct power factor for falling steel... because the targets have been designed for that. If you gun shoots heavy bullets well.... use them and get a slight advantage. If it doesn't shoot heavy bullets well... you will get more advantage out of using a bullet that you and your gun shoot best.

[IDescribe]

Heavier slower bullets have more dwell time on the target, allowing more time to build momentum in the target. So the theory goes. Whether or not that difference is significant enough to matter is a different story. It's one thing to say by way of physics that the advantage exists. It's quite another to the the advantage is worth anything in practice.

Much like the case with felt recoil -- IF slower heavier bullets had a significant advantage, the pros would all be shooting production with all metal pistols in.45ACP and 250gr bullets, and the number of them actually doing that is... zero?

[L3324temp]

Pros are willing to call for plate calibrations whenever needed. I just shoot local club matches and hate delaying the match to do so. Usually I just take the penalty. In my experience 135's loaded to the same power factor as 115's work better dropping steel.

[jim v]

Bullets with a flat nose knock down steel better than the equivalent round nose.

I believe that the tip of the round nose starts to shatter before the full effect is transmitted to the plate.

These results have been seen on poppers that were hard to move. The RN did not work, but the equivalent FP with the same PF worked.

[P.E. Kelley]

I did some testing....

http://ammoguru.com/pats-notes-from-the-field-freedoms-9mm-hush-165s/

[MarkCO]

The momentum difference is a few percent, and you really want little bit extra PF. It does not matter too much.

The load I use for popper calibration uses a 115 round nose loaded to 122 PF. I did test that load on a plate bolted to a 50 pound sled and an auto popper to measure how much the plate was pushed. The heavier bullets at the same PF moved both apparatus more than lighter bullets. HP bullets moved the plates more than round nose bullets at the same weight and PF.

The difference is probably less than the SD of most loads.