125 or 147gr. for USPSA

[njl]

I started out with 124s, did 147s for a while, and have settled on 135-138gr.  There's not quite as much load data, but it's a good compromise in bullet price and slide speed.

[IHAVEGAS]

On 7/28/2020 at 3:17 PM, zzt said:

Until you have actually tested this, you are guessing.

 

Any test data would be interesting.

[jim vaughan]

The bullet nose shape is a critical factor here. Flat noses will definitely put down poppers better than round noses

 

[IHAVEGAS]

7 hours ago, jim vaughan said:

The bullet nose shape is a critical factor here. Flat noses will definitely put down poppers better than round noses

 

Based on theory or based on testing and data?

[Joe4d]

On 7/28/2020 at 1:51 PM, Nc1911 said:

 I have some 115gr ammo that runs ~130PF, and it sometimes fails to knock down steel.
 

 

The power factor is power factor regardless of bullet weight.
115 grain at 130 power factor will knock down steel just as good as a 147 grain with the same power factor.  
 

  

 

On 7/28/2020 at 2:49 PM, Nc1911 said:

I agree that the hardness will effect how much energy is transferred into the steel, but mass x velocity produces the same amount of energy.

 

On 7/28/2020 at 3:04 PM, GearHead36 said:

Energy = K x mass x velocity^2. K is a constant. At the same PF, the lighter bullet will have more muzzle energy.

LOL,,, here is a tidbit. Foot lbs of energy formula is one great big lie as it pertains to bullets hitting things.
As folks above tried to tell you about steel,, as pretty much any big game hunter, especially ones with handgun and blackpowder experience will tell you, and if you really really still dont get it , bring your high foot lb of energy ammo to a bowling pin match.

Edited August 11, 2020 by Joe4d

[zzt]

11 hours ago, IHAVEGAS said:

Any test data would be interesting.

 

Sorry, no scientific data, just anecdotal evidence from testing.  This whole thing started because my minor 139 PF 180gr 40sw load was clearing pins much better than and of the 9mm loads, including the 147gr 144 PF factory loads.  All the 9mm shooters wanted to know why.  So we decided to do some tests.  There IS a reason why 45 200gr and 230gr bullets clear pins better than anything else.  I used to shoot 45 200s at those matches and won them all.  After a bunch of carping about winning all the time, I switched to my Limited gun shooting 40 minor.  I did not own a 9mm at the time.  I'll note as an aside that the yahoos who come with RN factory 230gr ammo shatter, but do not clear pins just cannot understand what is at issue here.

 

We started testing on pins, but quickly moved to poppers.  We carefully set the poppers so that a legal hit in the circular portion would drop the popper.  All ammo dropped the popper as long as it made minor.  The differences were in the speed the popper dropped, and how far off angle you could be  and still have it drop.  The further off angle you were the safer you were with the heavier bullets.  I'm still surprised a 132 PF 124 9mm cannot reliable drop a popper when shot from 45 degrees when hit in the round.

 

Then we went to falling forward steel.  Hit high with a 9mm it would fall, but you could take a nap waiting for it.  Unless it is in a USPSA match I want a 45 with 200s for that.  BTW, I shoot soft TC bullets in 40 and 45, except for bullseye.  There it is 200 LSWC.

[njl]

Anyone who's done much bowling pin shooting knows PF (momentum) and not muzzle energy is king when dealing with reactive targets.  A 115gr 9mm and 230gr .45acp can have nearly the same muzzle energy, but the .45 will transfer more energy to the pin.

[IHAVEGAS]

12 hours ago, zzt said:

We started testing on pins, but quickly moved to poppers.  We carefully set the poppers so that a legal hit in the circular portion would drop the popper.  All ammo dropped the popper as long as it made minor.  The differences were in the speed the popper dropped, and how far off angle you could be  and still have it drop.  The further off angle you were the safer you were with the heavier bullets.  I'm still surprised a 132 PF 124 9mm cannot reliable drop a popper when shot from 45 degrees when hit in the round.

 

 

Good stuff.

One day I would like to:

1. Gather some representative ammo.

2. Borrow a well built (consistent) popper from the local club.

3. Prepare a surface the popper sits on to prevent the popper shifting calibration during testing, maybe the popper sits on a 4x8 plywood sheet and spikes are driven through popper and holes drilled in plywood. 

4. Buy some 1" diameter stick on target circles.

5. Set popper at minimum safe distance from the bench where you will be shooting, say 8 yards. 

6. Determine the minimum elevation of the target circles for the popper to fall with each type of ammo tested, circles to be placed in horizontal center of popper. 

[zzt]

If you are going to go to all that trouble, why not test bullet shapes as well?  A while ago I was shooting pins using Penn Bullets 200gr RNFPBB bullets loaded to around 150 PF.  Everyone asked what the heck I was shooting, because the pins were disappearing as if by magic.  That bullet is semi-soft at 12-14 Brinell.  The reason it cleared pins so effectively was its very large meplat.  It was originally meant for Cowboy Action, but works perfectly well in 45 ACP.

[IHAVEGAS]

23 minutes ago, zzt said:

If you are going to go to all that trouble, why not test bullet shapes as well?

 

I think it is a good idea.

 

You can convince yourself that a wad cutter or truncated cone might "stick" to steel a little better and you can convince yourself that a round bullet would deform to the same shape all lead bullets take against the steel so it would not make any measurable difference. 

[belus]

6 minutes ago, zzt said:

If you are going to go to all that trouble, why not test bullet shapes as well?  A while ago I was shooting pins using Penn Bullets 200gr RNFPBB bullets loaded to around 150 PF.  Everyone asked what the heck I was shooting, because the pins were disappearing as if by magic.  That bullet is semi-soft at 12-14 Brinell.  The reason it cleared pins so effectively was its very large meplat.  It was originally meant for Cowboy Action, but works perfectly well in 45 ACP.

I've never noticed bullet profile changing the reaction of steel target. I think my own variance in where I hit it matters much more.

 

But imagining the bullet hitting the surface in slow motion, I can see how the edge of the flat point might bite and dig into the rounded wood surface of a pin a little better than a pointed profile on a glancing blow.  If the bullet has more mass it'll deviate less after the impact and continue to push the pin for a longer impulse.  I don't think bullet profile would matter as much striking the hard flat plane of a popper though.

 

Extrapolating from Newtonian penetrators, which is strictly a momentum analysis, I would think a longer projectile would be more effective than a shorter one for a given PF. This means heavier bullets, but it'd be neat if we had a test sensitive enough to see the difference between a Berry's hollow base bullet and a traditional solid. Maybe someone wants to build a momentum transfer pendulum device to test it?

Having written all the above I went looking for some actual studies, and I have to confess it's more complicated that I initially thought.  For example, momentum transfer gets less efficient from 500fps to 3000fps in this asteroid study, but then becomes more than 100% efficient as splatter recoils backwards off the target surface. https://apps.dtic.mil/dtic/tr/fulltext/u2/273315.pdf (figure 5)

And then to expand a bit on the length of projectile effect, bow hunters are apparently very concerned with not only bow poundage, but length of the draw stroke. F*dt = m*dv is the impulse and a longer duration a force can be applied the more momentum is stored. https://cpw.state.co.us/Documents/Hunting/EHU/Momentum-KineticEnergy-ArrowPenetration.pdf

[zzt]

Just now, IHAVEGAS said:

You can convince yourself that a wad cutter or truncated cone might "stick" to steel a little better and you can convince yourself that a round bullet would deform to the same shape all lead bullets take against the steel so it would not make any measurable difference. 

 

Physics makes me think the TC will be better on steel as well.  That is certainly true for pins.  I only shot soft TC bullets for competitions (except bullseye and Open) until recently.  I've been shooting a lot of 9mm RN and do not like how they perform.  I'm seriously considering switching to the Taccom Ultrafeed barrel/bolt system so I can shoot TCs and wide JHPs reliably.

[IHAVEGAS]

2 hours ago, zzt said:

Physics makes me think the TC will be better on steel as well. 

 

"In God we trust, everything else needs data"

 

 

[Farmer]

On 7/28/2020 at 11:21 AM, zzt said:

 

That is not true.  A heavier projectile at a lower speed transfers energy more efficiently than a faster, lighter projectile.  Try it yourself if you like.  We have, dozens of times and NO ONE who has tried both thinks the 115 is better.  I'll also say that softer lead is better than harder lead.  BTW, if shooting an outlaw match with uncalibrated steel, do definitely want 147s.  At my home club (not affiliated) the calibration is so bad I use 180 in 40sw or if 10-round limit in mag, 200 

Edited August 19, 2020 by Farmer
All ready covered.

[chgofirefighter]

It all boils down to your load data and other variables but what most important is your grip, your grip should be always the same regardless of the bullet weight.  Personally, I prefer 125gr for both major and minor power factor loads and I don't notice any noticeable difference between 125/135/147 etc minimal at best.  At the end day it all boils down to your personal preference and nobody can dictate that for you and lastly, fundamentals~!  Some will try to buy performance without putting in the work into improving their shooting skills and proficiency. Fundamentals, is prioirity numero uno~  

[twodownzero]

For 10+ years I had a strong preference.  Now after insisting that 147s were so flat, after all this time, I'm not sure I can tell the difference now.  I probably wouldn't shoot 115s, but the difference between 125s and 147s is a mag or two to get used to whatever minor difference there is.

[Cuz]

On 8/10/2020 at 8:08 AM, jim vaughan said:

The bullet nose shape is a critical factor here. Flat noses will definitely put down poppers better than round noses

 

Why do you say that?  I would expect equal weight and PF loads to flatten equally upon impacting the steel and therefore have a virtually identical effect on steel. 
 

although, technically, even if velocity was equal at the chrono 12 ft in front of the muzzle, wouldn’t the RN bullet have less drag and therefore more velocity 40ft away at the steel plate?

 

that could make the RN more effective...

[jim vaughan]

Shoot a flat nose cast bullet and a round nose cast bullet into a popper using the same weight and factor. The flat nose leaves a wide even indent in the steel of approx the size of the nose. The round nose leaves less of an indent and to me shows signs of the bullet fragmenting before full energy/momentum has been transferred. The impact pattern is radial and much larger than the bullet nose. I cannot say that fully jacketed bullets will give the same results.

[IF788]

I just tried 124s and there is a slight snappier feel to them.  I actually kind of like it.  weight will change your load to get to a given power factor, but assuming loads are adjusted to the exact same PF, this is largely personal feel, and there's going to be virtually no appreciable change to your overall match performance IMO.  if you have a good grip and your gun works its not going to affect you that massively.  however, if you try you may notice slight changes in recoil impulse and people have opinions either way.  That, and generally 147 cost more.   I have heard irons guys like 147s more and dot shooters like 124s more for a faster dot to return to zero.  there may be some truth to this - but again, if this going to win you a match or make your split times faster?  most certainly not.  

[shootin-blanks]

I choose SNS 135 RN, happy medium between slightly snappy 124 and the endless wait of 147's. 

[rowdyb]

the speed the slide travels and your perception of the sight returning are more a function of your recoil spring and your grip than your bullet weight.

[ilovevtac]

I personally prefer the 147GR as it feels softer.

[Guy Neill]

Just to throw it out there when thinking of shooting steel - remember what "killed" Peter the Power Meter"!

 

 

[Steve RA]

For those of us who didn't know "Peter the Power Meter", what did kill him ???  

[Guy Neill]

Peter the Power Meter was a ballistic pendulum that was used to determine the power factor of a load.  It had a steel plate that was shot and swung, with a scale to see how far it swung. .  The amount of swing determined whether or not a load made the power factor.  It was calibrated using 230gr FMJ from a Commander to establish Major power.  While they also established a Minor power factor using 9mm Luger FMJ ammunition, most shot Major using 45's.

 

It did not take a long time, but Charlie Funk and a buddie cast some pewter bullets in a nominal 200gr SWC mold that weighed, as I recall, about 135gr.  They were very hard.  They absolutely flipped the pendulum.  As a result, chronographs became the standard for determining the power factor.

 

This was actually predictable as an early method of hardness testing used a hammer to bounce off the material.  The higher the bounce, the harder the material.   Thereby, really hard bullets moved the steel pendulum plate much more than softer materials, like lead.