9mm fmj

[wcd]

Today i was trimming, and cutting the grass at the range. When cleaning up i found several nickle size remains of 9 mm fmj rounds on the ground below the steel plates. Which got me wondering about ammo in general, to me the fmj expanded in the sense that it was much larger in diameter, after impact. So now i am wondering if fmj has any expansion when hitting objects other than steel?

Also based on examination of the round it appeared to have lost some of its mass? If so where did it go, as it did not.appear to have fragmented.

 

[indykid]

Been shooting FMJ at steel targets and found it not unusual, if not the norm to find distorted rounds laying on the ground. If the round appears mainly intact, some loss of mass could be caused by vaporization as it mashed itself against the steel.

 

[rhino]

Today i was trimming, and cutting the grass at the range. When cleaning up i found several nickle size remains of 9 mm fmj rounds on the ground below the steel plates. Which got me wondering about ammo in general, to me the fmj expanded in the sense that it was much larger in diameter, after impact. So now i am wondering if fmj has any expansion when hitting objects other than steel?

Also based on examination of the round it appeared to have lost some of its mass? If so where did it go, as it did not.appear to have fragmented.

It's likely you were looking at just (or mostly) the copper jacket. Unless the jacket is bonded to the lead core, it's not uncommon for it to separate from the core upon impact with something hard. The lead part probably splattered/fragmented upon impact and where it went depends on how it hit and the way the steel is setup. Those shed jackets and pieces of them are typically what ricochets from steel and flies in unpredictable directions. Once the thing starts spinning and moving fast (after hitting the steel), it's shape and rotation combined with the air flowing past it can cause it to take a significantly curved path - think frisbee. I've seen shed jackets curve over side berms and back down into an adjacent shooting bay, or rather the end result. It makes an interesting sound when it does that too. The upside is that the jacket has a small mass, so if it hits something the potential to do damage is relatively small, but that's why we always wear eye protection!

 

[Cameramonkey]

And that deformation only happens on impact with extremely hard surfaces. Even bone doesnt seem to deform them all that much as I recall.

 

[russc2542]

And that deformation only happens on impact with extremely hard surfaces. Even bone doesnt seem to deform them all that much as I recall.

Nor does wood.

The missing lead turns to dust (essentially liquefying with the force of impact)

 

[HoughMade]

Besides steel? I'm guessing Tungsten, Titanium, Inconel...

 

[Disposable Heart]

The lead in most commercial jacketed ammo is pretty soft as it is using the jacket to prevent lead stripping and promote obturation of the bore during firing. That said, it's generally not soft enough to do much at pistol speeds. In rifle calibers is where you see tumbling and not fragmentation, the lead will start to 'squirt' out the bottom of the jacket when the jacketing is compressed, but again, not expanding necessarily to promote wound track.