Curious damage by bullets - explanation needed

[son-of-a-gun]

Dear forum members,

doing researches for investigative magazines here in Germany I have problems understanding some pics that show damages supposedly caused by 9mm bullets.
Lacking knowledge of ballistics I just can't explain those damages.

The first of two phenomenons I documented in the attached pdf file. Just ignore the german text and have a look at the pictures.

The phenomenon consists of nearly perfect(!!) circles that were broken (?) out of some windows allegedly caused by 9mm pistol stray bullets.

Those circles look like they'd been cut out by a glass cutter and are much bigger than the bullet itself.

Can anyone explain the mechanism that causes the glass to do that when hit by a 9mm bullet?

Because too big I had to make two parts
Side1-4
http://docdro.id/knIEtmJ
Side5-8
http://docdro.id/ctHXVRg

[Sequins]

That doesn't look like any 9mm impact on glass that I've ever seen, but the more important factor than the round used would be how the glass is treated. Do you know anything about how that sort of glass is treated in Germany? In America I'd assume tempered glass which really shouldn't behave like that, but perhaps you make glass differently in Germany.

In my own experience I've shot a pane of the kind of glass used in office buildings with a 9mm and it left tiny holes the size of the 9mm bullet but no larger. It looked basically like someone drilled a small hole- the rest of the glass wasn't impacted hardly at all.

[TXAZ]

It appears that the glass is safety glass.
I've seen a fair number of holes in a junk auto's windshield and side windows made with a much larger 12.7mm round. Those 12.7mm holes are significantly smaller than the holes in the pics you show. The size of the holes in your pic are, to this untrained forensic eye, more likely made by a ~ golf ball to baseball sized object, or a round rock.
My vote, if that's what you're tallying is that a 9mm couldn't possibly have made the holes in question, fired from a gun.

[K_Mac]

Not knowing the nature of the glass I would not bet the farm on it, but I think it is very unlikely the holes shown were made by a 9 mm bullet.

[jonnyc]

I threw a lacrosse ball through a large window once, looked exactly like the large holes pictured.

[TailGator]

In case someone argues that an expanding round made those holes, you should reply that expanding rounds do not expand to that degree. I'll join the choir and say that I have a hard time believing those holes were made by 9 mm rounds unless the glass has some very unusual qualities.

[son-of-a-gun]

Hello,

thanks for your opinions on that.

In America I'd assume tempered glass which really shouldn't behave like that, but perhaps you make glass differently in Germany.

One of the reference pics in my pdf origins from US - they don't refer to the gun used and the bullet size there.

https://www.nbcphiladelphia.com/news...202691811.html

The others refer to 9mm respectively the bullet shown in pics.

Now I just stumled upon that:

http://nypost.com/2016/12/20/shots-f...ooklyn-school/

Looking at the pic there IS a tiny hole BUT the glass seems to have had the tendency to break out like big holes I referred to, but it never did. Note the "darker" areas around the tiny hole.

It is also from importance I think that it is referred to these incidents as stray bullets - means these are not straight shots with full kinetic energy but shots that may have hit another target first - reformed bullets - and lost lot of their initial energy before they impacted in the glass.

Still it remains a mystery which maybe can rather be explained by some physics of the glass manufacturing itself.

[Salmoneye]

Spud Gun with balls of ice...

No evidence after the ice melts and evaporates...

My story, and I am sticking to it...

As for the 'School Window', much more likely it was a bird impact...

[T. O'Heir]

There's no way you can tell what made a hole in glass by just looking at the hole. Except on TV, of course. Ballistics has nothing to do with it.
House/building window glass isn't the same thing as car glass either. Building windows are not tempered like car windows.

[5whiskey]

There's no way you can tell what made a hole in glass by just looking at the hole.

I didn't vote because of this statement. I will say this... without having more information no one could speak with authority. Too many variables. Type of glass, any safety coatings applied, tint film, security laminates... plus was there any pre-existing damage to the glass? My instinct is to say that this is not likely to be damage from a 9mm round, but I have seen bullets do funny things in my days so I wouldn't rule it out.

[FrankenMauser]

I'd be looking for some stray golf balls, baseballs, or bricks...

[son-of-a-gun]

There's no way you can tell what made a hole in glass by just looking at the hole.

That's very true BUT if people claim the hole has been caused by this or that than one can try to get near the probabilities for that.
The search for truth is always very hard and one can only get nearer to that step by step and sometimes one has to take a step back.
I would at that point not exclude that any bullet caused that holes. Meanwhile I think this is the wrong end to investigate. Rather I should go to a physics board or a glass experts board.
What if glass is very thin and untempered? Then a bullet hitting that will cause to break to whole window in 1000 pieces. Effect: A huge hole. Would someone have guessed that a bullet did this? Or rather some guys with baseball bats?

[Minorcan]

I said ai don't know because it is impossible to tell from a picture. But to me it looks like a larger slow moving object. Maybe a ball or rock?

[Aguila Blanca]

Originally Posted by T. O'Heir

There's no way you can tell what made a hole in glass by just looking at the hole. Except on TV, of course. Ballistics has nothing to do with it.
House/building window glass isn't the same thing as car glass either. Building windows are not tempered like car windows.

Is the cartridge shown in the second link supposed to be the type of round that made the holes? It appears to be a .38 Special or .357 Magnum -- which is, of course, the same diameter as a 9mm, but, technically, isn't referred to as a "9mm" except when describing the caliber in metric units.

What catches my eye about it is that it's a flat-point bullet. Supposedly (I'm not a hunter, so I don't know), flat-point bullets are more damaging in tissue that round nose or spire-point bullets. Perhaps the same holds true when flat points hit glass.

It might make an interesting experiment.

[Aguila Blanca]

Originally Posted by Minorcan

I said ai don't know because it is impossible to tell from a picture. But to me it looks like a larger slow moving object. Maybe a ball or rock?

In my misguided youth I broke more than a few windows with rocks, baseballs, footballs, BB guns, and various other projectiles the classification of which has been lost to the mists of time. The only ones that made neat, round(-ish) holes were the BBs. Large, slow moving objects tended to just take out the entire window (or the entire pane, in the case of multi-pane window units).

[FrankenMauser]

I must also admit to having broken, or witnessed the braking of many windows.
Thrown baseballs usually take out the entire pane, but hit baseballs often leave round holes.
Rocks are very similar to baseballs - low speed smashes, high speed pokes a hole.
Golf balls, at least in my experience, are often moving fast enough to leave holes.
Bricks like leaving a circular or elliptical hole if they hit with a corner first - especially in laminated windows ('energy' type, not 'security' type).

The oddballs were horseshoes. I never saw an entire window taken out by a horseshoe - only holes.

[son-of-a-gun]

Is the cartridge shown in the second link supposed to be the type of round that made the holes? It appears to be a .38 Special or .357 Magnum

Yes, this appears to belong to that revolver depicted used on a killing spree in Austria late 90s. And the picture on page 6/8 shows the corresponding hole it is said to have caused.

The only ones that made neat, round(-ish) holes were the BBs.

Quite interesting - after I read this:

Most BB-firing airguns can shoot faster than 60 m/s (200 ft/s). Some airguns have the ability to fire considerably faster, even beyond 170 m/s (560 ft/s)

That would be compared to Beretta 9mm (365 m/s) pistol maximum half the speed.

Now we seem to get somewhere: If we assume the holes didn't come from straight shots through the window (as they refer to as "stray bullets") the pistol shots may have "ricocheted" from any other surface they hit first - reforming and loosing lot of their initial velocity.

Than they would behave like the much slower BB-gun bullets, right? With the ability to create such "neat, round(-ish) holes"....
For whatever reason...

It might make an interesting experiment.

That's a very good idea. Unfortunately I neither own a gun nor have the experience and place to set that up maybe one of you guys can conduct an experiment. The sad point is that we would need a "ricocheted" bullet which are hard to calculate where they will go. Might be dangerous. And then different types of window-glass with different depths from thin untempered glass to thick tempered one. Might be interesting if that roundish holes appear somewhere...

[WW2]

Those look like the holes I made in my house window when I hit a golf-ball size rock with my lawn mower. Nice round hole just slightly larger than the rock.

[Aguila Blanca]

You won't get a hole in tempered glass. Any fracture of tempered glass and the entire pane disintegrates into roughly pea-sized, round-ish fragments.

I don't think it's low velocity that creates holes, I think it's high velocity. As someone above mentioned a thrown baseball versus a hit baseball. It was the faster baseball that made the hole, not the slower.

And I believe the flat-point bullet is significant. It's not a wadcutter, but I recently tested a .380 ACP pistol with several different brands of FMJ ammo. All but one were round-nose. The exception was a round-nose, flat-tip. And that one made much cleaner holes in the paper targets I was using.

[son-of-a-gun]

@Aguila Blanca

The only ones that made neat, round(-ish) holes were the BBs.

Let us stick to the BB guns you used:

You wrote of

"neat, round(-ish) holes"

So what was the size of the holes compared to the size of the metal balls fired with the gun?

Our main problem remains that the shown holes in all those windows are way bigger than any bullet and we still need a proper explanation for that.

What especially amazes me is that degree of accuracy and precision (specially the inner) hole in this pic is cut out:

http://s3-eu-west-1.amazonaws.com/de...3a-768x432.jpg

And to repeat: The bullet shown in the little plastic bag is supposed to have achieved that!!!

http://s3-eu-west-1.amazonaws.com/de...4a-768x432.jpg

[Mal H]

Given the multiple images shown, the poll is useless so I closed it.

[son-of-a-gun]

Sorry for the poll and good to see there is a strict administration in here some other boards are in need of

The multiple images have one thing in common:

Allegedly they show damages made by stray bullets what leads one to a general question.

Why do holes need to be round? If I threw a square brick through a window would the "hole" be round or square?

Would those holes also be roundish if bullets were square?

Obviously no one in here can give a logical explanation for the phenomenon, so after the weekend I will put up my second issue as written in the starting post. It's a strange impact in a car.