View Full Version : Clear Ballistics Gel and Perma-Gel
I know Dr Roberts has said Perma-Gel is not a good tissue simulant for testing. Is the same true of the Clear Ballistics gel?
What makes Perma-Gel (and possibly Clear Ballistics Gel) poorly suited for testing? They seem to offer some advantages (temperature stable, clear, and they won't mold/rot) but I don't want to waste my time if any results with them are useless.
AndrewWiggin
12-04-12, 10:23
I'm not sure. I've heard the same thing but no one has offered an objective, empirical reason. I'd like to see a series of tests with well documented rifle, pistol, and shotgun rounds to determine whether it produces results consistent with calibrated 250A bloom gelatin or not. If it doesn't, well, there's your answer. If it does, then it may simply be some institutional inertia at work.
I think there's a big disconnect between what is suitable for a lab doing government contract work and what is suitable for the private citizen looking to determine in a very general way what the performance capabilities of a particular cartridge are.
Man, I might be way off base with this comment, but here goes...
10% gel is not any better at being a tissue simulant than perma gel, but it is the industry standard and thus used to compare load to load.
Where this gets sticky in my mind is that the permagel results may be close to 10% but they are not identical and thus the temptation is to compare permagel results to 10% results and that would not be an accurate comparison.
on the flipside, some guys are doing a BB calibration before they shoot (and getting correct pentrations)... could that be used to compare to 10%?
So, heres the cool part. There is a guy on youtube (tnoutdoors9) who does a ton of permagel tests and actually does a half decent job at measuring and comparing the results. he's got a large enough body of comparative testing at this point that one could begin using those results constructively.
To be honest, I compared a bunch of tnoutdoors9 shot results to Doc and others 10% results and they are very very close. close enough that for my purposes a well done permagel shot is good enough for me to begin my own experiments and testing.
as a cool aside, this is the ONLY area that anything new is being done for the 10mm, and it's yielding some good and (mostly) predictable results, further validating it in my mind.
I still focus on shot placement and frequency as my primary means of wounding tho:p
AndrewWiggin
12-04-12, 10:55
That's a good point. Clear Gel, Permagel, Simtest, and even calibrated 10% ordnance gelatin, for that matter, are not very good at predicting what bullets will do in tissue. For that matter, what bullets *did* in tissue is not very good at predicting what bullets *will* do in tissue. What 10% ordnance gelatin is good at is being a consistently repeatable medium that allows different people to compare bullets in a meaningful way.
Tnoutdoors9's tests are generally consistent with well published loads, in the areas that he has tested something that was also tested by a "real" lab. It bothers me that he only posts his BB calibration depth and not the velocity, though. Most of his 10mm tests have been consistent with mine, though one test was dramatically different. He got way different results from Underwood's 180gr Gold Dot than I got from a hand load of the same bullet at the same velocity range.
Shawn Dodson
12-04-12, 16:20
That's a good point. Clear Gel, Permagel, Simtest, and even calibrated 10% ordnance gelatin, for that matter, are not very good at predicting what bullets will do in tissue.
The test of the wound profiles’ validity is how accurately they portray the projectile-tissue interaction observed in shots that penetrate the human body. Since most shots in the human body traverse various tissues, we would expect the wound profiles to vary somewhat, depending on the tissues traversed. However, the only radical departure has been found to occur when the projectile strikes bone: this predictably deforms the bullet more than soft tissue, reducing its overall penetration depth, and sometimes altering the angle of the projectile’s course. Shots traversing only soft tissues in humans have shown damage patterns of remarkably close approximation to the wound profiles.
The bullet penetration depth comparison, as well as the similarity in bullet deformation and yaw patterns, between human soft tissue and 10% ordnance gelatin have proven to be consistent and reliable. Every time there appeared to be an inconsistency…a good reason was found and when the exact circumstances were matched, the results matched. The cases reported here comprise but a small fraction of the documented comparisons which have established 10% ordnance gelatin as a valid tissue simulant.
--“The Wound Profile & The Human Body: Damage Pattern Correlation.” (Martin L Fackler, MD, Wound Ballistics Review, 1(4): 1994; 12-19)
Tnoutdoors9's tests are generally consistent with well published loads, in the areas that he has tested something that was also tested by a "real" lab. It bothers me that he only posts his BB calibration depth and not the velocity, though. It's unfortunate that Tnoutdoors9 misinterprets disruption produced by temporary cavitation and describes it to his viewers as permanent disruption. The "damage" produced in his test simulant does not correlate to damage produced in soft tissues.
AndrewWiggin
12-04-12, 16:39
Let me clarify: I'm not saying that ballistic gelatin results are without merit. I'm just saying that the interaction of a projectile and tissues often involve many variables that are difficult to reproduce or control for. Ballistic gelatin is the industry standard tissue simulant and it is perfectly adequate for the intended task. Other mediums may perform well but I am unaware of any testing that indicates whether the results from the other mediums are analogous to 10% ordnance gelatin.
AndrewWiggin
12-04-12, 16:45
I agree. The first few times I heard it I thought he had misspoken but it seems he is unaware of what TSC and crush cavity actually are. Nevertheless, his measurements are thorough enough that you can draw your own conclusions, if you believe his medium to be reasonably similar to 10% ordnance gelatin.
Shawn Dodson
12-04-12, 17:29
I'm just saying that the interaction of a projectile and tissues often involve many variables that are difficult to reproduce or control for.
I understand what you're saying but these "many variables" really don't matter.
AndrewWiggin
12-04-12, 17:42
I think we're quibbling over a matter of scale.
I know Dr Roberts has said Perma-Gel is not a good tissue simulant for testing. Is the same true of the Clear Ballistics gel?
What makes Perma-Gel (and possibly Clear Ballistics Gel) poorly suited for testing? They seem to offer some advantages (temperature stable, clear, and they won't mold/rot) but I don't want to waste my time if any results with them are useless.
This PDF has information on the recent development of physically associating (copolymer) biomimetic gels
http://www.dtic.mil/dtic/tr/fulltext/u2/a481959.pdf
and offers favorable comparison of these newer tissue surrogates to calibrated ordnance gelatin in terms of their mechanical response to the passage of projectiles- namely density, bulk modulus, short-time and long-time strain rates, and radial inertial properties- the chief advantage being that the copolymer gels offer greater thermal stability than ordnance gelatin.
The clear gels being used most recently seem to be of this class of material, but there doesn't seem to be a lot of correlative research that would serve to establish their dynamic equivalence with calibrated ordnance gelatin. It would be nice to see more.
AndrewWiggin
12-06-12, 08:48
Correct me if I'm wrong, and there's a pretty good chance of that. It seems to me that for the layman, we are really only concerned about the depth of penetration and the size of the expanded projectile, if expansion occurs. We already know, in a general way, how various projectiles interact with tissue based on earlier professional gelatin tests. If a series of tests done with one of the newfangled gels shows performance relatively consistent with 10% ordnance gelatin, wouldn't that indicate that future tests should be similar? What I mean is that it seems like those gels are *close* even if they aren't exactly the same and *close* is probably good enough for most of us, right?
Correct me if I'm wrong, and there's a pretty good chance of that. It seems to me that for the layman, we are really only concerned about the depth of penetration and the size of the expanded projectile, if expansion occurs. We already know, in a general way, how various projectiles interact with tissue based on earlier professional gelatin tests. If a series of tests done with one of the newfangled gels shows performance relatively consistent with 10% ordnance gelatin, wouldn't that indicate that future tests should be similar? What I mean is that it seems like those gels are *close* even if they aren't exactly the same and *close* is probably good enough for most of us, right?
That all depends upon what degree and quantity of cross-correlational research one is willing to accept as being "adequate". My preferences are more in line with the major researchers like Doc Roberts and Fackler (so far only water and calibrated ordnance gelatin are correlated) in the field, while someone else may be just fine with a somewhat lesser degree of correlative agreement.
This is not to say that I am not in favor of seeing the development of more thermally stable mediums (water is the closest to that at this time), but until there is more research like the PDF I linked to (above) my personal preference is stick with the two known quantities. With that thought, I'd sure enjoy seeing more work done in that area.
If you are interested in the topic, both MacPherson and Schwartz have books out that deal with water and gelatin test mediums here-
http://www.amazon.com/Bullet-Penetration-Modeling-Incapacitation-Resulting/dp/0964357712
and here-
www.quantitativeammunitionselection.com
:)
AndrewWiggin
12-06-12, 20:55
This isn't going to be popular, but here goes:
Water's correlation to 10% ordnance gelatin is somewhat tenuous. I understand that Doc Roberts advised Old Painless that water typically demonstrates approximately 1.8-2x the penetration observed in gelatin (IIRC) but this apparently only applies to service caliber pistol ammunition. The relationship is dramatically different with rifle caliber ammunition and I suspect it may vary substantially with higher velocity pistol ammunition. For example, I've shot 75 gr Prvi Partisan BTHP into water and witnessed less than 18" of penetration, which would be less than 10" in gelatin. Molon's test of the same ammunition shows roughly 14" of penetration in gelatin and my own, less scientific, gelatin test shows the same results.
I'm not trying to disagree so much about Cleargel, etc. I simply am not qualified to make a statement either way.
This isn't going to be popular, but here goes:
Water's correlation to 10% ordnance gelatin is somewhat tenuous. I understand that Doc Roberts advised Old Painless that water typically demonstrates approximately 1.8-2x the penetration observed in gelatin (IIRC) but this apparently only applies to service caliber pistol ammunition. The relationship is dramatically different with rifle caliber ammunition and I suspect it may vary substantially with higher velocity pistol ammunition. For example, I've shot 75 gr Prvi Partisan BTHP into water and witnessed less than 18" of penetration, which would be less than 10" in gelatin. Molon's test of the same ammunition shows roughly 14" of penetration in gelatin and my own, less scientific, gelatin test shows the same results.
I'm not trying to disagree so much about Cleargel, etc. I simply am not qualified to make a statement either way.
As for the relationship between gelatin and water tests, I'd go with what Doc Roberts said. The experts- Dr Roberts, Dr Fackler, Dr DiMaio, Mr MacPherson, Mr Schwartz, Mr Wolberg, and many others too numerous to recall- have done the research and weighed in with what seems to be a pretty decent concensus. It (water) works.
Heck, there's even a Fackler box (a test rig used for doing water tests) named for none other than Doc Fackler himself.
I've paid (dearly :D) for three gelatin tests of my SD ammo in the past and look forward to the day when we'll see an inexpensive, available, thermally stable test medium that has been found to be every bit the equal of calibrated ordnance gelatin.
I can dream. :p
I've paid (dearly :D) for three gelatin tests of my SD ammo in the past and look forward to the day when we'll see an inexpensive, available, thermally stable test medium that has been found to be every bit the equal of calibrated ordnance gelatin.
Since I hear that ballistic gel is such a pain to use, isn't it time to change the standard to a user friendly material that is close to the old gel?
As for the relationship between gelatin and water tests, I'd go with what Doc Roberts said. The experts- Dr Roberts, Dr Fackler, Dr DiMaio, Mr MacPherson, Mr Schwartz, Mr Wolberg, and many others too numerous to recall- have done the research and weighed in with what seems to be a pretty decent concensus. It (water) works.
Heck, there's even a Fackler box (a test rig used for doing water tests) named for none other than Doc Fackler himself.
I've paid (dearly :D) for three gelatin tests of my SD ammo in the past and look forward to the day when we'll see an inexpensive, available, thermally stable test medium that has been found to be every bit the equal of calibrated ordnance gelatin.
I can dream. :p
Why mess with gel? I simply mail ammo to people who hunt hogs and have them snap pictures of the recovered slugs (if any) and the autopsy as they butcher the animal along with their impressions. You get an idea of what works and what doesn't, albeit you don't have cubic cm of "just like tissue" crushed to bandy about on the internet.
Gel is useful for comparing one round to another, and is a good simulator, but performance in gel details performance in the real-world is the argument...so performance in the real world will parallel performance in gel, is the other side of that argument. Pigs are cheaper than gel. So if I want to know how a round does in gel, shoot a pig. It works both ways, so to speak, although performance on the pig matters more than the gel, imo.
Since I hear that ballistic gel is such a pain to use, isn't it time to change the standard to a user friendly material that is close to the old gel?
I wouldn't mind seeing that happen. Looks like it is on the way according to the PDF I posted (#10) above.
Guess we'll just have to be patient.
Why mess with gel? I simply mail ammo to people who hunt hogs and have them snap pictures of the recovered slugs (if any) and the autopsy as they butcher the animal along with their impressions. You get an idea of what works and what doesn't, albeit you don't have cubic cm of "just like tissue" crushed to bandy about on the internet.
Gel is useful for comparing one round to another, and is a good simulator, but performance in gel details performance in the real-world is the argument...so performance in the real world will parallel performance in gel, is the other side of that argument. Pigs are cheaper than gel. So if I want to know how a round does in gel, shoot a pig. It works both ways, so to speak, although performance on the pig matters more than the gel, imo.
Long before I start sending ammo to others, I'll go do a hog hunt myself.
Why should they have all the fun? ;)
AndrewWiggin
12-07-12, 12:17
As for the relationship between gelatin and water tests, I'd go with what Doc Roberts said. The experts- Dr Roberts, Dr Fackler, Dr DiMaio, Mr MacPherson, Mr Schwartz, Mr Wolberg, and many others too numerous to recall- have done the research and weighed in with what seems to be a pretty decent concensus. It (water) works.
Heck, there's even a Fackler box (a test rig used for doing water tests) named for none other than Doc Fackler himself.
I've paid (dearly :D) for three gelatin tests of my SD ammo in the past and look forward to the day when we'll see an inexpensive, available, thermally stable test medium that has been found to be every bit the equal of calibrated ordnance gelatin.
I can dream. :p
Even when you can clearly observe that water does not maintain a linear relationship to gelatin in regards to velocity?
Even when you can clearly observe that water does not maintain a linear relationship to gelatin in regards to velocity?
Especially so.
Consider the yields of MacPherson's and Schwartz's bullet penetration models- www.quantitativeammunitionselection.com -plotted on a Cartesian graph. Both models' yields (which are always nearly identical) plotted on such a graph describe a logarithmic curve with V along the ordinate and D along the abscissa. A linear trendline (it's kind of an "average", if you will) drawn through either of these model's yield curves will diverge significantly from either model's logarithmic curves where the velocity is below about 600 fps or above about 1100 fps with the linear "average" grossly over-estimating terminal penetration depth at both extremes of the curve in the vast majority of the cases.
The deceleration of a bullet in water or gelatin is not a linear function.
AndrewWiggin
12-07-12, 13:14
Okay. I hear a lot of folks throwing around the 1.8-2x figure as if that applies equally.
Okay. I hear a lot of folks throwing around the 1.8-2x figure as if that applies equally.
That number is just a general estimate and I suspect that Doc Roberts' value is the best of both worlds. I've seen that figure run from 1.5x to 3x depending upon whom one is listening to.
If you want to "convert" terminal ballistic performance in water to terminal ballistic performance in gelatin there are only two equations that I know of that'll do the job- the Schwartz and MacPherson bullet penetration models.
I prefer to use them both (and average the results) and they agree with one another unbelievably well given that they are two entirely different sets of equations.
Why mess with gel? I simply mail ammo to people who hunt hogs and have them snap pictures of the recovered slugs (if any) and the autopsy as they butcher the animal along with their impressions. You get an idea of what works and what doesn't, albeit you don't have cubic cm of "just like tissue" crushed to bandy about on the internet.
Gel is useful for comparing one round to another, and is a good simulator, but performance in gel details performance in the real-world is the argument...so performance in the real world will parallel performance in gel, is the other side of that argument. Pigs are cheaper than gel. So if I want to know how a round does in gel, shoot a pig. It works both ways, so to speak, although performance on the pig matters more than the gel, imo.
The problem is that people will kill a hog or a couple hogs and draw conclusions based on a very small sample size. It can certainly give you useful information but since no two hogs are exactly the same and no two shots are exactly the same it can lead to people drawing incorrect conclusions when good ammo seems to perform poorly or when bad ammo seems to perform well.
With a large sample size you can draw conclusions with a less consistent medium. If you shot hundreds of hogs with a specific load in nearly the same manner you could draw stronger conclusions, but that is not an easy thing to accomplish. Gel gives a consistent medium to compare different ammo directly with a much smaller sample size because it minimizes variables. Isolating variables is at the very foundation of scientific testing.
As for switching to a different medium for testing, I'm all for it if we can accomplish that without compromising reliability. One of the reasons the current ballistic gelatin is preferred is because it has already shown to correlate with real world shootings. Changing away from something we know works isn't something to be done without careful consideration.
I'm not sure. I've heard the same thing but no one has offered an objective, empirical reason. I'd like to see a series of tests with well documented rifle, pistol, and shotgun rounds to determine whether it produces results consistent with calibrated 250A bloom gelatin or not. If it doesn't, well, there's your answer. If it does, then it may simply be some institutional inertia at work.
I think there's a big disconnect between what is suitable for a lab doing government contract work and what is suitable for the private citizen looking to determine in a very general way what the performance capabilities of a particular cartridge are.
Wrong. Doctor Roberts has directly stated that Perma Gel doesn't work, and there are no other tissue simulants currently in use that compare to 10% ordnance gelatin. In the case of Perma-Gel - it was tested by Doctor Roberts and found to be unsuitable as a tissue simulant, although it was useful as a backer material when testing ballistic vests.
The best suggestion I have for you is to read Duncan McPherson's book on the subject that explains what is required of a good tissue simulant. It takes longer than I care to type out. Suffice it to say: There is certainly a desire to use tissue simulants other than ballistic gel due to gel's sensitivity in how it's prepared and the fact that you can only store blocks for two days. The Army is currently conducting research into physically associative gels (PAGs). I don't yet know how likely they are to replace properly calibrated BG.
Long before I start sending ammo to others, I'll go do a hog hunt myself.
Why should they have all the fun? ;)
Id love to,but cant right now.
AndrewWiggin
12-10-12, 09:29
Wrong? What is wrong? That private citizens may or may not demand the same level of accuracy? That's an expression of an opinion and simply can't be right or wrong.
I think what you're getting at is that the gelatin substitutes aren't suitable for lab use. I'm sure you are correct. You know a whole hell of a lot more on this subject than I do but you can't possibly be trying to say that they aren't useful at all, to anyone, because multiple tests performed by independent people have shown reasonably accurate results, compared to published data on well known cartridges. If a wide range of pistol, shotgun, and rifle tests show penetration and projectile upset results roughly consistent with published results from ordnance gelatin, that is sufficient for me. Am I going to base my decision on carry ammo on it? Not likely, but it is interesting.
It is interesting to see data on cartridges and loads that haven't seen a lot of testing. I respect you but until someone can give me a quantitative reason that I should ignore the similarity between these mediums and calibrated 10% ordnance gelatin, I am going to maintain the position that they are reasonably analogous. Not precisely the same but close enough that I can say "Wow, nice expansion and adequate penetration," or "Holy fragmenting piece of crap, Batman, that thing didn't even make six inches!"
I'll still keep 180 gr Gold Dots in my G23 and I'll still keep 75 gr Prvi Partisan in my home defense rifle.
Many of the polymer gel simulants we have seen are OK for rough handgun penetration data, but generally fail to adequately capture and represent the TSC associated with rifle caliber projectiles. As a result, at this time they are not the best choice for a tissue simulant.
Water is a less than ideal media, but is simple and cheap--giving a rough assessment of maximum expansion characteristics of JHP handgun projectiles.
To date, adequately prepared, correctly stored, and properly calibrated ordnance gel remains the best simulant for assessing penetrating projectile characteristics. When interpreted correctly, it does have a very good track record at accurately reflecting results of actual shooting incidents involving human tissue--it is not just useful for comparing projectiles to one another.
Many of the polymer gel simulants we have seen are OK for rough handgun penetration data, but generally fail to adequately capture and represent the TSC associated with rifle caliber projectiles.
Doc, could you give us some rough numbers on gel simulants for handgun calibers? What are typical discrepancies compared to ballistic gelatin (in %) when you measure expansion and penetration?
AndrewWiggin
12-12-12, 08:26
Thanks for the reply, Doc. I have noticed that the tests people post with Cleargel show almost no TSC. Do you think the penetration figures for rifle cartridges would be fairly close (within an inch or two) of the results from ordnance gelatin?
Thanks for the reply, Doc. I have noticed that the tests people post with Cleargel show almost no TSC. Do you think the penetration figures for rifle cartridges would be fairly close (within an inch or two) of the results from ordnance gelatin?
Necropost!
I'd like to know this, too. But even more so, I'd like to know the difference between clear gel and "Ordinance gelatin" when it comes to pistol calibers.
Do pistol bullets tend to penetrate more, or less, or does it "depend"?
In a nutshell: It depends, but usually more.
Due to the different resisting forces involved in clear gel as compared to ordnance gel at different velocities, not only does clear gel produce results that are different from 10% organic gelatin, but you also can't create a conversion formula that would allow you to translate figures from one into the other. In fact, you can't necessarily even compare 2 bullets to each other in clear gel, in the sense that a bullet that penetrates more in clear gel may not necessarily penetrate more in tissue.
In practice, this usually manifests itself as a seemingly variable increase in the penetration of rifle rounds, along with a decrease in not only the degree but also the likelihood of fragmentation/expansion. Safe to say that clear gel should be largely disregarded as a good testing medium for such projectiles, at least for gathering the information you'd usually want to see out of such a test. (Arguably, clear gel is useful as a worst case "check" on expansion/fragmentation reliability, much as with the 4-layer denim test in handguns, but this is highly subject to debate.)
With handguns...again, from a physics standpoint, we can't easily predict how bullets will perform in relation to clear gel. In practice, the numbers usually seem to be pretty similar, at least with the service calibers. I've observed that handgun rounds tend to penetrate about 5% more and expand about 5% less in clear gel as opposed to organic gel, with the caveat that this ratio is by no means guaranteed technically and is just an approximation based on numbers collected on the internet.
For the hobbyist who just wants to get a basic idea of how a pistol bullet performs, I think it's probably close enough in most cases. If you want more exacting numbers, especially when testing an unknown loading or producing industry data, 10% organic gel is definitely the way to go.
So, one could say that if a pistol bullet doesnt penetrate "enough" clear gel it will do even less in ordinance gelatin?
Highly likely, but I couldn't guarantee it from shot to shot. It may be possible that, in select cases, the properties of clear gel will actually cause a bullet to penetrate less.
Generally speaking, though-if a handgun round doesn't usually attain sufficient penetration in clear gel, much less ordnance gel, I'd say that's a good reason to steer clear.
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