9mm enigma

[John Van Gelder]

It is spring here, such as it is.. I have been out checking the places I did any shooting over the winter picking up bullets after the snow melted. I picked up a 9mm bullet, that seems to be a bit of an aberration. I have been experimenting with soft lead, in the 9mm, just because it is easier/cheaper to find than harder alloy.

The bullet I found stared off as a Lee 125 gr. RNFP probably pretty close to straight lead. After firing the bullet turned into nearly a cylinder, almost a wadcutter, with only slight rounding on the leading edge, the bullet was just over .1" longer than the original and miked out to .349". I slugged the barrel on the gun it came from and the gun has a .356 barrel.

The recovered bullet had rifling engraved nearly the entire length of the bullet.

Over time I have shot a lot of soft lead bullets in various hand guns, most notably some pretty hot stuff in the .357 magnum, I have not observed this particular phenomenon. My guess about the cause is the extremely fast rate of twist in the 9mm, almost every other handgun on the planet has a much slower twist.

[Taterhead]

Piqued my curiosity. Do you have a pic, by chance?

[Sig556r]

I would likewise be curious to see pics...

[tazman]

Soft lead is relatively easy to deform. Having the nose slump on a soft lead bullet in a relatively high pressure cartridge(which the 9mm is) is a common occurrence.
I have seen pictures on this site of boolits that were not even as soft as yours sounds like it was, slump from a round nose or RNFP to nearly wadcutter shape.
Most of these were either 357 mag or 44 mag but the pressures are still near that range in the 9mm.

[Black Jaque Janaviac]

Yeah. I've paper patched pure lead RNFPs for .357 Mag and recovered them from the snow. The lube grooves were obturated out completely as in you couldn't tell they existed, and there was noticeable nose slump.

I have no explanation as to why yours would have increased in length and decreased in diameter (to a point less than the groove diameter). Unless gas blow-by squished it down - but then you would think the rifling would not be visible.

[John Van Gelder]

I have also paper patched soft lead for the .357, using the 358429 bullet the ones recovered from show were "barrel swaged" into RNFP, these were loaded with the max load of 4227, accuracy was always good.

A couple of years ago I loaded some soft lead 160 grn SWC bullets in the 9mm, with just enough 700X to work the action. I recovered one of those from snow and it had spun off into a nearly symmetrical dumbbell shape narrow in the middle with rounded ends. I wish I had taken a picture of that, but it has long since gone into the lead pot.. The recent 125 I recovered is on the bench and I will post a picture.

[tazman]

I have heard that snow will do strange things to boolits.

[John Van Gelder]

I have a pile of .45ACP bullets recovered from the snow that could be lubed and shot again.

[John Van Gelder]

Here is the picture 239569

[tazman]

Interesting. I have no idea about the smaller diameter and extra length.

[gwpercle]

The numbers don't add up . Bore = .356 , fired boolit = .349 ?????
Has the meplat grown in size ? The crimp groove is totally obliterated .
Soft lead usually fills the bore .
The rifling on the fired boolit is quite sharp...
What gun were you shooting these in ? and do you have any other recovered boolits....do they all look like this ?
Something strange is going on here ...

[Bulldogger]

My first (and only) guess is that that recovered odd boolit followed a squib load that was stuck in the bbl and got jammed into it, causing the deformation shown...

[gwpercle]

My first (and only) guess is that that recovered odd boolit followed a squib load that was stuck in the bbl and got jammed into it, causing the deformation shown...
And get smaller ???? That's the part that throws me.. the recovered boolit should be .356 not .349?

[Dusty Bannister]

"The bullet I found stared off as a Lee 125 gr. RNFP probably pretty close to straight lead. After firing the bullet turned into nearly a cylinder, almost a wadcutter, with only slight rounding on the leading edge, the bullet was just over .1" longer than the original and miked out to .349". I slugged the barrel on the gun it came from and the gun has a .356 barrel."

Perhaps you could zero the mic and measure to verify the major diameter and again the minor diameter. Do not take an average reading, but take several readings around the diameter of the bullet as well as at each end of the "cylinder" you have shown. Snow might distort the body of the bullet so it is flattened on one side, but would barely be visible. If you start with a bullet sized to 358" and push it through a smaller hole, it will get longer. Does the barrel have an even number of grooves and lands? Dusty

[Tom Myers]

About the only explanation that I can see is that the barrel might have an odd number of grooves.

[John Van Gelder]

The gun I shot these bullet in is a CZ 75 copy, just for comparison I dropped the bullet into the barrel and it fell all the way through, there is no place on the bullet that is still bore diameter. I was unable to recover any other bullets, apparently this went into deeper snow, the other made into the ground. The squib theory does not work these were experimental loads so every time the hammer fell something came out of the barrel.

I recovered several .45 bullets and they are all .451 (all from the same alloy as the 9mm) . Based on the obvious rifling marks on the bullet, indicating that it filled the bore, what ever happened occurred outside of the gun. Here is a video about spinning 9mm bullets on ice. https://www.youtube.com/watch?v=QEXTGlNe0J0

My guess, is that this is caused by high rate of rotation due to the fast rifling twist. All of the other semi auto guns use a much slower twist 1-16 or better 9mm Makarov 1-19.

Here is a formula for calculating bullet RPM: MV x (12/twist rate in inches) x 60 = Bullet RPM for my loads at just over 1000 fps the spin comes out to 72,000 rpm. Between forward momentum and the angular velocity, I think the bullets are stretching. Lots of recovered hard alloy/fmj bullets and they are still bore diameter or original diameter, there are lots of manufacturers that use less than .355 bullets in their fmj load offerings. .

Accuracy of these loads seems to be pretty good, sample has been pretty small.

[popper]

Boolits shrink dia. and lengthen when going down the barrel. Lots of lube spread over the barrel to shrink dia also. Then there is the barrel shock response (using fast powder) - chamber expands, shock wave goes down barrel, expanding and CONTRACTING it. Short pistol barrel it shows up on recovered. Larry G & Goodsteel had a problem with 'stretched' GC shank - same problem and GC friction worsens it.

[Black Jaque Janaviac]

Popper, if this is ordinary behavior, why don't we see this more often? It seems like it is more typical for a fired bullet to have the same dimensions as the slug you pushed through by hand.

[scattershot]

Are you sure it was your bullet?

[DocSavage]

The rate of twist for my CZ 75 ,92FS are 1 in 10. Now I have 4 1911s of different makes one of them might be 1 in 16 but it seems IIRC 1 in 10 is the factory norm. I've never seen a cast bullet deform like that 9

[mdi]

Are you sure it was your bullet?

This is what I was thinking. I've only been casting 30 or so years and never heard of bullets getting longer or shrinking in diameter, but I've never shot into snow...

[blackthorn]

Buddy with a sense of humor?

[dverna]

No way the bullet diameter will get reduced under bore diameter.

Make sure the reading is correct by measuring a non deformed bullet.

If you have five groove barrels, there is a procedure to measure the bullets from them

[JBinMN]

Did you weigh it, and compare to the other ones weight?

If it weighs a bit different, perhaps it is another type of boolit.. I dunno.

If it came out of the same firearm, then it #1, should be the same size as the groove diameter and similar to others you fired in the same place & in the same way. #2, there should be more than one of them out there, since you said you have been shooting that same firearm "doing experiments with soft lead", and #3, I would think it should be a repeatable event, even without snow, by shooting into a barrel of water perhaps.
Anyway, that is how I understand they check firearms that are suspected to be involved in a shooting to look at the boolit & compare lands & grooves on it after firing, to try to match projectiles to a particular firearm. Kind of similar to fingerprints...

Not ever heard of such a thing as what is described..

[Priusron]

If the bullet just falls through the barrel, there is no way it was fired from that weapon. You need to check your other weapons. Does anyone else use your range, with or without your permission?

[marek313]

If the bullet just falls through the barrel, there is no way it was fired from that weapon. You need to check your other weapons. Does anyone else use your range, with or without your permission?

I agree. I dont believe thats the same bullet.

[Kenstone]

Send a 2019 calendar to the OP
He was 8 days late on posting/starting this April Fool
:bigsmyl2:

[John Van Gelder]

No one else shoots where I do it is private property,with limited access. I know for a certitude it came from one of my 9mm guns and which one it was. I am not sure shooting into water will provide the same result, if you shoot JHP bullets into water they will expand.

I am still inclined toward centrifugal force. I have a friend of mine that has his own forensics lab, we worked a number of homicides together, I will pass this on to him and see what he thinks.

[gwpercle]

Why have you only found one boolit ? All the boolits fired should look like this.

Until I see a few more fired boolits I'm going with a theory...
Ancient Alien Technology !
my go to excuse for anything I can't explain !

[Black Jaque Janaviac]

I will trust your certainty that you have the right bullet matched to the right gun. But I don't follow how centrifugal force could cause the phenomena we are observing. When the bullet spins this would cause a force tangential to the circumference and, if anything, would cause the diameter to expand, and lenght to shorten. Think pizzeria guy spinning dough.

[John Van Gelder]

If the bullet is longer, then it follows that the diameter would decrease. I have seen this before a couple of years ago when I was shooting 158 gr, soft lead SWC bullets in the 9mm. I found a couple of those bullets when the snow melted and they were severely distorted.

However in this case a sample of one is not enough to formulate an accurate conclusion.

I tried to shoot some bullets into water, but it was not deep enough, the bullets went through the water into the mud. Perhaps I need to make up one of Paul Harrell's "High tech fleece bullet stops."

[WheelgunConvert]

We’re any plated or jacketed projectiles in the mix?

[bedbugbilly]

Interesting. Looking at your photo - I don't question that it is the same as the unfired example based on the lube groove and crimp groove. Like everyone else - the diameter of the fired boo lit is puzzling. I also wondered if you kew for sure it was one of "your" bolts but what caliber of pistol/rifle would create the diemeter of the "changed" boolit? None come to mind for me.

I guess I would ask what you were shooting at where you recovered the boolit? A target of some nature or just plain snowbank? I' not a scientist by any means - what say others about a soft lead boolit going down a barrel - hot from friction in to a cold snow bank? Any others that you recovered similar to the one pictured?

Would love to know the reason for the fired boolit ending up in the given die,eter/shape.

[John Van Gelder]

Just a shot at a pine cone on top of the snow, there was also a layer of ice under the snow, and the bullet was recovered in about 6" of water after the snow and ice melted, probably a good month between the shooting and when I found the bullet. As above I shot several .45s into the snow up on the same ridge and recovered almost all of them. they could be lubed and used again, they were all of the same alloy as the 9mms.

The .45s were in the 850 fps range from a 1-16 twist barrel as compared with 1000-1100 in a 1-10 barrel.

[WheelgunConvert]

How’s about from a small caliber muzzle loader? The twist looks a bit too fast, but would account for the deformities towards the nose.

[John Van Gelder]

WheelgunConvert

No..the bullet in question definitely came from my CZ75 clone. I have forwarded the explanation and pictures to a forensics lab.

[ioon44]

Could be the barrel is leaded so badly that the bullet is coming out with the small diameter.

[JBinMN]

Could be the barrel is leaded so badly that the bullet is coming out with the small diameter.

I would guess that would be unlikely due to the rifling impressions on the boolit that is in the pic.
http://castboolits.gunloads.com/attachment.php?attachmentid=239569&d=1554901005&thumb=1

I would think that if the grooves were leaded enough to constrict the boolit, they would not show up as pronounced as they look in the picture above.

I still think it is a puzzler...

[Black Jaque Janaviac]

If the bullet is longer, then it follows that the diameter would decrease. I have seen this before a couple of years ago when I was shooting 158 gr, soft lead SWC bullets in the 9mm. I found a couple of those bullets when the snow melted and they were severely distorted.

However in this case a sample of one is not enough to formulate an accurate conclusion.

I tried to shoot some bullets into water, but it was not deep enough, the bullets went through the water into the mud. Perhaps I need to make up one of Paul Harrell's "High tech fleece bullet stops."

Right, but centrifugal force due to rifling will not elongate the bullet. The only way I could think would be if the bullet started tumbling, then the force could stretch the length. But if the elongation and narrowing occurred after firing (tumbling) then I don't think we'd see the nose slumpage, unless that occurred before leaving the bore.

[John Van Gelder]

I believe the mechanism here is that the bullet was swaged in the barrel, and the elongation occurred after it left the barrel, range to the target was 49 of my paces, there was time for the bullet to tumble.

[John Van Gelder]

Black Jaque Janaviac

Too bad I did not offer a prize for the best answer. I spoke with my "forensics guy" and his best guess is tumbling, however he is not sure that would have worked for such a short bullet. He advised that the best test medium is snow..which I hope not to see in any significant quantities for at least 6 months.

After all of the dialogue about this matter, I recall that one shot, and at the time I only fired three at the target pine cone, went low and left, while the other two were on target, went through the snow into the ground. My best guess right now is that the one I recovered was the low left shot, and that it was so far off because of tumbling.... Another friend of mine who used to be one of the moderators on this forum, advised that one guess was probably as good as any other..

Thanks to one an all for all of the responses..

[popper]

I shot some 99% PB 165gr TC from 40SW a few years back, tumbled and left a rectangle on the target (but L.G. didn't collapse). None recovered but when sized they come out smaller (thus tumbled). PB doesn't have any spring back so if you shrink it- it stays there. You use lube in the groove that flows and sizes the boolit more. I didn't see tails in the L.G. so assume it was sized pretty close to bore to begin. Basically, normal for soft alloy in high pressure case.

[John Van Gelder]

popper

Good idea..I will shoot some of the soft lead bullets on paper a various ranges and look for "rectangles"..