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Best bullet profile for knockdown steel


vgdvc

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Hello all and happy New Year! Given the same bullet weight and load/(same pf)for the same caliber (ex. 9 mm) has anyone noticed a reasonable difference in knockdown ability on steel comparing different projectile nose type profiles? Specifically round nose versus flat point. Especially if steel plate is hit on somewhat of an angle. Thanks

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4 hours ago, jim vaughan said:

Flat nosed bullets work best with minor factor.


what are you basing this on?  
I guess technically, if you are considering the possibility of hitting the outside edge of the plate like 1mm on the edge, then the full wad cutter bullet would be king. 
 

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11 hours ago, Toolguy said:

Bullet weight is King on reactive targets. The heavier the bullet, the better it works.

To a certain extent maybe but velocity is key as well. A 9MAJOR 115 knocks down steel better than any minor mouse fart load 147

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We run 9mm Everglades 115gr RN plated right at PF in 3 different pistol & PCCs and have never had a problem knocking over falling plates, Texas Stars, poppers(large&small), and spinners in 3gun & USPSA. Have run 124's & 147s and have not noted any significance difference. 

 

gerritm

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Something I've thought about doing:

1. Borrow a good reliable popper from the local club.

2. Mark elevation on popper with say 2" vertical graduations.

3. Determine minimum height where bullet drops popper consistently.

4. Play about with bullet shapes and weights while holding power factor near constant (say 130) and see how that effects minimum elevation. 

 

I think until someone does something like this, we are just guessing. 

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The larger the meplat the faster and more efficiently the energy is transferred.  I tested this with a lot of my 45 ACP loads.  I used ploy coated TC, LSWC, RNFP and Penn Bullets wide metlap bullets, all in 200gr.  I forget the specific name of the Penn bullet.  Powder charge was the same for all.  I had chrono'd three of these loads and they were all very close.

 

All dropped steel, even poorly calibrated large poppers, without issue.  The difference was in the speed of the drop.  Believe it or not the slowest falling was with my buddies 230gr RN.  TC and SWC were next.  The Penn bullet was by far the fastest falling.  The RNFP was a tad faster than the TC/SWC, but I hadn't chrono'd it, so I don't know if was bullet shape or an increase in velocity that made the difference.

 

I also discovered bullets in the 12~15 Brinell range felled faster than 21 Brinell bullets.

 

Another observation:  one of the clubs I shoot at only allows forward falling steel.  If you've shot them you know they are slow to fall.  So slow sometimes you are better shooting the next two or three targets instead of waiting t see if it fell.  Targets hit with SS major loads fall faster than when hit with by 115gr @ 1470 fps 9mm major load.

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Anecdotally, I'll submit that on spinners my 115gn 9mm major JHPs are way more effective than my 230gn .45 LRNs at the same power factor. If any kind of an angle is introduced the difference is way more pronounced. My theory is that the JHP in flattening gets more dwell time on the spinner to apply work, and that it gets more 'bite' at an angle. Other observations that I have tested and proven are that for me heavier bullets work better than lighter ones on spinners. Specifically, in 9mm 147rn more gooder than 115rn, and in .223 75gn more gooder than 55gn. Your happy place may be different than mine.

 

As far as knockdown steel in USPSA, if I call a good shot I'm moving on way before waiting to hang around and watch something fall. Who's got time for that? Doesn't matter what I'm shooting, the bullet weight or the profile. The only way a good hit isn't going to drive steel down is a REMF of some kind. If I call an edge or a low hit, that's no bueno and the target gets smacked again wether it needs it or not.

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14 hours ago, JWBaldree said:

If I call an edge or a low hit, that's no bueno and the target gets smacked again wether it needs it or not.

 

I hear ya, but that doesn't work for forward falling steel.  I just shoot once at everything in the array and reengage any that are still standing.  The first time I encountered forward falling steel in a USPSA match, I hit the first one and didn't see it move.  So I hit it again with four rapid, centered shots.  I stopped and said wtf.  It fell.  My additional shots were just propping it up.  My squad mates had a good laugh.

 

BTW, what is a spinner?

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20 hours ago, JWBaldree said:

If any kind of an angle is introduced the difference is way more pronounced. My theory is that the JHP in flattening gets more dwell time on the spinner to apply work, and that it gets more 'bite' at an angle.

This is the kind of observations I'm inquiring about. My thought is a flat point would have less deflection than round nose possibly transfer more energy. If true this can make a significant difference on a match that is all knock down steel by the end of the day

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1 hour ago, vgdvc said:

This is the kind of observations I'm inquiring about. My thought is a flat point would have less deflection than round nose possibly transfer more energy. If true this can make a significant difference on a match that is all knock down steel by the end of the day

 

Spinners are NOT knock-down steel.  Generally speaking, knock-down steel is "supposed" to fall if you hit it, otherwise it's not properly calibrated.  Normally, with a decent hit, even sub-minor ammo will work fine.  But, I use the same 9mm load for all the games I play, so I'm using Minor PF.  In my G17 steel gun it chrono's around 126 PF.  In my Carry Optics G34 it's around 128, and in my other G34 it's around 132.

 

 

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USPSA poppers are calibrated to a floor of 115.

 

2. Prior to commencement of a match, the calibration ammunition must be chronographed using the procedure specified in Appendix C2. The calibration ammunition, when tested through each designated firearm, should achieve a power factor between 115.0 and 125.0 to qualify. 9x19 mm is the recommended caliber.

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The problem usually occurs when using a cast 9mm round nose projectile at minor factor. These seem to disintegrate before passing on their full knock down force.

The same weight bullet with a flat nose has always taken down poppers with more authority than the round nose.

The calibration procedure usually uses military style jacketed round nose bullets which obviously do not disintegrate in the same manner.

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21 hours ago, jim vaughan said:

The problem usually occurs when using a cast 9mm round nose projectile at minor factor. These seem to disintegrate before passing on their full knock down force.

The same weight bullet with a flat nose has always taken down poppers with more authority than the round nose.

The calibration procedure usually uses military style jacketed round nose bullets which obviously do not disintegrate in the same manner.

Jim,

I am definitely NOT calling you a liar, because I have not done any testing to confirm or deny what you are saying, but it just doesn’t make sense to me how this can be the case in reality. Maybe in a laboratory, and in a vacuum or something. But not on a range, with actual steel targets. 
 

The only time I can envision bullet profile making a difference is in extreme edge hits where less than half the bullet head impacts the steel. Then a RN profile could glance off the edge and not impart enough of its force on the steel, but a full wadcutter would impart more force on the steel. 
 

But, I wonder if the feeding reliability you may give up by shooting wadcutters would be worth it. 
 

This is just my uninformed/unconfirmed/untested opinion. 

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On 1/5/2022 at 8:59 AM, jim vaughan said:

The problem usually occurs when using a cast 9mm round nose projectile at minor factor. These seem to disintegrate before passing on their full knock down force.

 

This is actually quite true.  The harder the lead, the more splatter, the less energy transmitted.  You can see this at any steel challenge match by looking at the splatter pattern in the ground just in front of each target.  Then watch a cowboy action match.  Those soft bullets slam the steel.  At the end of the match you'll find a pile of flattened lead disks under each target.  Italian artillerymen figured this out in the middle ages.  They watched their hard stone balls bouncing off castle walls, doing little damage.  When they switched to soft iron balls, all the energy was transferred and the walls came down.

Edited by zzt
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7 hours ago, vgdvc said:

This is generating more interesting  content than I anticipated 👍


lol, yeah, but did you get the answer you were looking for?

 

Reliable feeding in your gun, reasonable velocity, and hitting the target are much more important factors than bullet profile. 
 

I “think” everyone will agree to that. 

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9 hours ago, Cuz said:


lol, yeah, but did you get the answer you were looking for?

 

Reliable feeding in your gun, reasonable velocity, and hitting the target are much more important factors than bullet profile. 
 

I “think” everyone will agree to that. 

My original post was to see if anyone had noticed any performance advantage on knockdown steel,all other factors being the same, with the only differential being bullet profile. Not using a lower power factor than required , not sacrificing reliability and not missing the target.

 Yes, I did receive some valuable information from those who recognized there are some differences in certain situations and scenarios.

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