Is gel testing realistic?

[Unobtanium]

I have began to wonder, given my experiences with my own back-yard tests, if the gel-testing data we are seeing is realistic in a sense. Most of the gel shoots happen at very close distances. With a pistol round, in the capacity of a police or self-defense shooting, this is very realistic and applicable. Further, gel replicates tissue very well, as has been shown. But is the METHOD of testing realistic when extrapolated to anything but 0-12 yard shootings?

I began questioning this, as I started testing shotgun slugs in water jugs. Water jugs are probably one of the most "expansion inducing" targets you can shoot. Rounds that do mediocre in tissue or gel will often expand amazingly, picture perfect, in water. Also of note, SWIFT bullet company uses water tanks for their testing, as well! They seem to be turning out bullets that work in the real world, too.

So I fired some rounds into water jugs. Federal Truball LR, at 25 yards, was first.

25 yards is NOT a long shot for a slug, in fact, 25 yards is now within "buckshot range" for many, with the Flite Control wads now used.

My Federal Truball expanded to...0.763" at the widest point. I then tested Hydrashok LR, which expanded to an average of 0.8"

This is NOT what federal's published gel data suggests should happen. Not even CLOSE.

I am left with 3 possibilities.

1# The LE packaged ammo I got from an LE distributor is defective.
2# For slugs, and no other round I've tested, water doesn't cause expansion.
3# The data collected by Federal was generated at a much closer distance than the 5 yards at which I shot.

I tend to lean strongly toward #3, which brings me full circle to my topic header. Is gel testing realistic for the typical use of the ammunition? In pistol calibers, I would say "absolutely", but regarding rifle and shotgun slug? I raise questions.

[DocGKR]

Well, we have conducted gel testing of rifle projectiles out to 600 meters. Ensure the testing is done for the most likely engagement distances you would face (ex. 3 meters, 25 meters, 100 meters, 300 meters, 600 meters, etc...) then it should work very well, as long as it is properly conducted.

[Unobtanium]

Well, we have conducted gel testing of rifle projectiles out to 600 meters. Ensure the testing is done for the most likely engagement distances you would face (ex. 3 meters, 25 meters, 100 meters, 300 meters, 600 meters, etc...) then it should work very well, as long as it is properly conducted.
That was a specific instance though, not industry standard like the 10ft or whatever seems to be, no?

[Erick Gelhaus]

This is NOT what federal's published gel data suggests should happen. Not even CLOSE.


If I may ask, what is the information that Federal provides for those rounds in your caliber?

[Tokarev]

FBI protocol is (or was anyway. Maybe still is?) to test handgun ammo through various barriers at ten feet followed by a test through auto glass at 20 yards. I believe they also test rifle ammo from a distance of 50 yards.

Here's a bit of data although some (or all) has probably changed over the year.

https://www.americanrifleman.org/articles/2015/4/16/throwback-thursday-the-fbi-ammo-tests/

[TGS]

Let me get this straight:

You shot some water jugs in your back yard, and are using the results from such to question the validity of IWBA/FBI protocol gel testing?

[Unobtanium]

Let me get this straight:

You shot some water jugs in your back yard, and are using the results from such to question the validity of IWBA/FBI protocol gel testing?

Correct. Bullets over-expand in water, yet I am seeing significantly LESS expansion. Are shotgun slugs super special and not like any other bullet I've tested? Or...do they lose velocity faster, and Federal is testing them at very close distances.

[the Schwartz]

Correct. Bullets over-expand in water, yet I am seeing significantly LESS expansion. Are shotgun slugs super special and not like any other bullet I've tested? Or...do they lose velocity faster, and Federal is testing them at very close distances.

Since water is actually a valid test medium, why not use it? With all of the issues surrounding the recent use of synthetic test mediums like Clear Ballistics Gelatin (which overstates penetration depth and under-represents expansion), why not use a test medium that already meets with FBI and IWBA approval? There is a reason that the Fackler box uses water after all.

[Unobtanium]

Since water is actually a valid test medium, why not use it? With all of the issues surrounding the recent use of synthetic test mediums like Clear Ballistics Gelatin (which overstates penetration depth and under-represents expansion), why not use a test medium that already meets with FBI and IWBA approval? There is a reason that the Fackler box uses water after all.
Every bullet I've ever fired into water looks like a bare gel bullet, except expansion in some cases has been very slightly more. I've never ever until now had the opposite.

Water even correlates to penetration in tissues after corrective factor.

[Zhukov]

Water only gives you part of the picture, ie. the ideal expansion. Gelatin will give you much more interesting data in regards to the bullet's overall performance. Granted - for pistol bullets that's not a huge factor but it is for rifle bullets. Neck length to yaw, temporary and permanent cavity size, etc.

[Unobtanium]

Water only gives you part of the picture, ie. the ideal expansion. Gelatin will give you much more interesting data in regards to the bullet's overall performance. Granted - for pistol bullets that's not a huge factor but it is for rifle bullets. Neck length to yaw, temporary and permanent cavity size, etc.

That's what's so odd, the slugs I am testing expand only 25% as much as they do in gel. I've never seen that from water as a medium before.

[Zhukov]

Yeah, that is weird. My guess (and that's all it is) is that slugs might behave differently in water than other projectiles.

[Unobtanium]

Yeah, that is weird. My guess (and that's all it is) is that slugs might behave differently in water than other projectiles.

That was what I was arriving at and curious about. My take on it (a guess as well):


Regular JHP's expand due to force within the HP cavity.
Slugs expand because of resistance across the face.
I will note that the "hollowpoint" in every truly HP slug I have ever fired is "blown out" (hydraulic pressure pushes a hole through the front of the slug at this location).

The rest of the slug compacts, and expands radially.

I think maybe slugs do not expand as well in water because they do not meet as much frontal resistance as in gel or tissue.

Mulling it over, that's the best I can come up with. A correlation would be an FMJ pistol round into water vs. gel. You're more likely to see a slight bit of deformation from the gel strike.

[SiriusBlunder]

From http://www.le.vistaoutdoor.com/downloads/catalogs/Shotshell_Data_Book.pdf:

Shotgun: 870 Cylinder Bore • Barrel: 18.5 inches • Range: Muzzle 10 ft. from front of gel block

[the Schwartz]

Every bullet I've ever fired into water looks like a bare gel bullet, except expansion in some cases has been very slightly more. I've never ever until now had the opposite.

Water even correlates to penetration in tissues after corrective factor.

Yes, there are even equations for that 'conversion' if you wish to pursue it.

Both MacPherson (Bullet Penetration) and Schwartz (Quantitative Ammunition Selection) have them; both researchers rely upon modified Poncelet penetration equations correlated against actual gelatin test data.