ballistic gel test question

9

9ballbilly

New member
I hope this is posted in the correct forum.
After a short trial and error period I mixed up my first batch of ballistic gel using a formula I'm told is identical to that used on the T.V. show "Mythbusters".
(Knox unflavored gelatine is the primary ingredient). I plan to use the gel to test two self-defense loads: .45acp handloaded with 230gr XTP
.38spl+P 125gr JHP (Win. personal defense loads)

The best mold I had on hand was a small cooler which will give the gel block
9" of depth. My question is, should I expect more than 9" of penetration with
either of these loads? More so with the .45 as I want to know if I'm getting enough velocity for the bullet to perform as it should since I don't have access to a chronograph. Thanks, Bill

P.S. This is my first experience with ballistic gel
 
The FBI penetration standard is 12 inches of ballistics gel, and most defensive hollow points will exceed that by a few inches. You can try stacking two blocks back to back, and that will give you a better idea of penetration.
 
Thanks for the input guys. I'm going to make a second block so I've got enough depth.
Also, it seems to make sense to cover the front of the block with some sort of cloth to imitate clothing. Something that I wouldn't have thought of
 
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When I tested a 125 Gr XTP @ 1350 FPS into wine boxes filled with water at 15' it penetrated 4 boxes & stopped in the 5th. That's about 21", but with water not gel.:cool:

You definitely need more backup.:D
 
There is a debate about Knox gelatin being the equivilant of ordnance gelatin.

One thing that you'll want to do is calibrate it by firing a .177 steel BB at 590 feet per second (fps), plus or minus 15 fps, into the gelatin, resulting in 8.5 centimeters (cm), plus or minus 1 cm, penetration (2.95" – 3.74").
 
The FBI Heavy Clothing test

Test Two - Heavy Clothing - The gelatin block is covered with four layers of clothing. One each of the following:


◦cotton t-shirt material (approx 48 threads per inch & 5.25 ounces per square yard)

◦Cotton dress shirt material (approx 85 threads per inch & 3.5 ounces per square yard)

◦A down comforter (500-550 fill power) in a cambric shell (approx 232 threads per inch)

◦Denim (approx 50 threads per inch & 14.4 ounce per square yard)

The shots are fired to not impact on a stitch line of the comforter.
 
The YouTube test

You buy some uncooked pork ribs at the grocery store, cut the seat portion off an old pair of jeans, stick the pork ribs in the rear pocket of the jeans and secure that to the front and center of the gelatin block.

Shoot through the pork ribs :D

I have no idea what this test tells us but YouTubers are fond of doing it.
 
COuntZerO, The only reason I can imagine for the youtube test is to imitate the bullet passing through clothing and striking bone. That's quite a bit deeper than I plan to get into it as well as making consistent results impossible to obtain due to too many variables (angle bullet strikes bone, bullet passes between bones, etc.).
My .177 pellet gun fires them at 1,000 fps. so if penetration is about 60% more,
4.72"-5.98" does that mean the gel is approximately the correct consistency?
Thanks, Bill
 
I'm just saying the YouTube pork ribs test is silly because it's highly variable and the test is no basis for comparing rounds to each other especially when the standard is ordnance gel.

It's like going to one car dealership and learning a car model get 34 mpg and going to another car dealer and learning their model goes from zero to 60 in 9 seconds. And you're going to compare the two cars how ???

If you can't get a proper calibration it gets tricky to get good results but a guy by the name of Duncan MacPherson figured out how to adjust results within certain parameters - the BB can't deviate by more than 2" either way, and I don't beleive his equation can be applied above velocities of 620 fps. It's in his book: MacPherson, Duncan (1994). Bullet Penetration: Modeling the Dynamics and the Incapacitation Resulting from Wound Trauma
 
Actually the more I think about it...

Block density is the variable, and you're trying to normalize results for a BB that penetrates more deeply than 3.74"

If the BB itself can't be shot within a certain velocity range (605 fps although MacPherson's formula seems to work up to 620 fps), you're introducing a new variable and there's no way to calibrate your block.

590 is typical spring propelled BB speed, we're talking a copper BB, not a lead pellet...
 
O.K. Thanks,
I'm just trying mainly to find out if my .45 XTP will expand correctly so that I can adjust the load accordingly. I have no idea what the debate is between Knox and ordnance gel. I used Knox because that's what the recipe I was given called for and it was readily available at a local store. I'm going to make another identical block (which will give me 18" of depth) and try it. Another member posted that 12" is the F.B.I. standard for .45acp penetration so I'll try standard factory 230gr FMJ and adjust the consistency until I get that result. Thanks very much for letting me pick your brain.
 
Here's the expansion I got from the .357 test I posted about earlier, I imagine you'll get similar results.
DSCF8324.jpg
 
Another member posted that 12" is the F.B.I. standard for .45acp penetration so I'll try standard factory 230gr FMJ and adjust the consistency until I get that result.
Click to expand...


Why would you do that? FMJ should penetrate far more than 12 inches. I'd think fmj would go more than 20 inches.
 
12" is the minimum, it's not necesarily ( IMO ) optimum.

The Winchester 45 Auto Bonded-230gr RA45B penetrates to 14" and expands to .73" in bare gel - that's darn good performance - one hekuva round IMO.
 
9ballbilly, A Fackler Box would probably be easier to use and set up:

2mrfsjt.jpg


All that's needed are one-gallon size ziplock storage baggies and some water..
 
Thanks again guys. I haven't seen a Fackler box before. I might have misunderstood what was said earlier in the post. I thought that the F.B.I. standard meant that a .45acp with factory ammo should reach 12" of penetration. I was going to use that as a way of calibrating the consistency of my home-made gel. This post has been very educational to me and I really can't thank you guys enough!
This leads me to my next question. Is there a standard penetration depth for factory .45 RN FMC ammo that I can use for calibrating my gel?

P.S. Wogpotter, anytime you need help empying those wine boxes don't hesitate to ask :D:D
 
I think the problem that you still face is what equation / what values do you apply to any results you get.

Here is the why Duncan MacPherson's formula is used. It takes a lot of time and effort to create ordnace gel blocks. When the FBI did their tests, if a BB traveling at roughly 590 fps plus or minus 15 fps, penetrated less than 2.95" or more than 3.74" they discarded that block. They didn't use it for testing.

Actually I think that's still the FBI's policy - but they are a huge agency and they have the money to do that.

What Duncan MacPherson's formula allowed people to do, is take a block that doesn't meet the specifications, and still use it to get testing results. The bullet may penetrate more or less in the out-of-spec block, but based on the BB results - the test results for the bullet can be adjusted or normalized using MacPherson's formula.

MacPherson could take those same equations and create a table for some standard round - like Winchester Silvertip or something, but he hasn't.

To my knowledge, the only table available is for a BB traveling roughly 590 fps. As I said before MacPherson's table maxes out at 620 fps.

If you want test results that mean anything, you first have to have a way of propelling a BB at around 590 fps. Then you can start shooting it into your Knox gelatin to see if it is penetrating more shallow or more deeply than would be expected in ordnance gel and nail down the exact recipe needed for you Knox. Then when you've got a good recipe, you can run your tests and get good results. And your results will be validated by having a BB penetrate the gelatin roughly 3"
 
9ballbilly: said:
This leads me to my next question. Is there a standard penetration depth for factory .45 RN FMC ammo that I can use for calibrating my gel?
Click to expand...

Sure. Applying the correct values to MacPherson's formula, a 230 gr. FMJRN @ 835 fps should penetrate to a depth of 29.3195 inches in calibrated 10% ordnance gelatin.
 
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