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.
Last edited by 481; 12-07-12 at 13:29.
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.
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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.
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.
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?
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