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Old 09-28-2010, 06:25   #1
Tomac
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Water to Gel Conversion Factor?

There's a conversion factor to convert water penetration to appx gel penetration. Anyone happen to remember what it is? Thx!...
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Old 09-28-2010, 11:24   #2
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I don't know if there is a true formual, but I find penetration in water about double what you get in gel.
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Old 09-28-2010, 17:28   #3
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I've seen conversion values ranging from 1.80 to 2.50.

For calibrated 10% ordnance gelatin to water, "2.25" has always been the closest conversion factor in my personal experience.
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Old 09-28-2010, 17:36   #4
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I thought it was 1.2:1 or 1.5:1 but I don't remember w/any degree of certainty.
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Old 10-02-2010, 23:27   #5
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I thought it was 1.2:1 or 1.5:1 but I don't remember w/any degree of certainty.
Tomac
I believe that is correct. If you went with 2.5:1 and had a bullet penetrated 14" in gel. You would need 35" of water. I rarely (read never) see a hollow point bullet that expanded go beyond 24" of water.
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Old 10-03-2010, 23:50   #6
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I believe that is correct. If you went with 2.5:1 and had a bullet penetrated 14" in gel. You would need 35" of water. I rarely (read never) see a hollow point bullet that expanded go beyond 24" of water.
I've posted a lot of JHP test results that go well beyond 24".

This .45auto/230gr Golden Saber loaded upper 900s penetrated a 1/10" hard steel barrier and exited #5 water bottle. Four bottles popped their caps, #1 exploded and #2 split wide open; all from a 'non-penetrating' caliber. Pic has been posted on GT a number of times during the past 4-5 years;

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1:2.25 appears to be a very close gel to water ratio.

I have more data for the furniture penetration thread, probably time to post it.

A number of JHPs tested on that thread penetrated in the 28"-32" range.

Bob
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Old 10-04-2010, 06:48   #7
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For what it's worth, here's a link w/water jug testing of a *lot* of 9mm loads w/the vast majority penetrating 24" or less:
http://stevespages.com/page8f9mmluger.html
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Old 10-04-2010, 08:03   #8
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I am not doubting you and I have had JHP's that did not expand go well beyond 24". 24" is about 4 gallon jugs, which I use with a back up. For a JHP that expands it is almost always in the 3rd of 4th jug. Yesterday I shot a 357 sig 125gr GD going at over 1,500fps and it was in the 2nd jug.
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Old 10-05-2010, 15:28   #9
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I am not doubting you and I have had JHP's that did not expand go well beyond 24". 24" is about 4 gallon jugs, which I use with a back up. For a JHP that expands it is almost always in the 3rd of 4th jug. Yesterday I shot a 357 sig 125gr GD going at over 1,500fps and it was in the 2nd jug.
Wow, that's terrible performance for the 125gr GD.

This 230gr Hornady TAP ammo bullet almost made it out the back of #3 bottle;

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The following pics show some water bag tests that I did with the 9mm/147gr GD; I was very surprised that the 9mm performed much better than the 10mm/165gr Golden Saber.

Sheetrock barrier, the set-up;

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One water bag is about 8" of water penetration and the bags need side support to keep them upright.

What I saw after the trigger was pulled;

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The 147gr Gold Dot penetrated the sheetrock w/o plugging and came to rest after penetrating 40" of water;

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The 10mm/165gr GS bullet had jacket separation and came to rest in #3 bag.

A 147gr XTP mid 1100s/.38Super/0.580" retained 85% of it weight and penetrated through 31" of water bags.

Bob
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Old 10-05-2010, 17:36   #10
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Question: Bullets fired through jugs have to penetrate numerous plastic jugs and not just water. Wouldn't penetrating the plastic have a negative effect on total penetration?
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Old 10-05-2010, 20:35   #11
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Question: Bullets fired through jugs have to penetrate numerous plastic jugs and not just water. Wouldn't penetrating the plastic have a negative effect on total penetration?
Tomac
Not really, it just pushes it out of the way. The plastic isn't that thick. My biggest issue testing in water is the bullet likes to curve off line & water is surprisingly "hard" @ high vel impacts & can make even a poor designed bullet expand. Wetpack is "mushy", closer to gel & seems to yield better results. Still, it's fun shooting stuff.
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Old 10-06-2010, 18:44   #12
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Question: Bullets fired through jugs have to penetrate numerous plastic jugs and not just water. Wouldn't penetrating the plastic have a negative effect on total penetration?
Tomac
Probably not noticable, this 125gr XPB 'dented' a plastic bottle used as a back up behind plastic bags;

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Heckuva thing when thin plastic stops a bullet.

Bob
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Old 10-06-2010, 23:35   #13
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Probably not noticable, this 125gr XPB 'dented' a plastic bottle used as a back up behind plastic bags;

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Heckuva thing when thin plastic stops a bullet.

Bob
It does kind of show how little energy/momentum an exoanded bullet has after passing through a given medium. If that bullet hit someone, it might leave a nasty little bruise.
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Old 10-07-2010, 13:00   #14
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It does kind of show how little energy/momentum an exoanded bullet has after passing through a given medium. If that bullet hit someone, it might leave a nasty little bruise.
Yeah, I was surprised to see how effectively the XPB sealed off the hole, not one drop of water out of the hole. I guess the water in the bottle was compressed to some insignificant degree.

Relying upon my memory, which can be 'iffy' at times, doesn't a bullet need about 180fps-230fps in order to puncture skin???

I think my German Shepherd has given me larger bruises than this XPB would have caused after exiting water bags. But, since bruising was your idea, would you like to send me some of your skin for testing?

Bob
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Old 10-07-2010, 14:00   #15
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Yeah, I was surprised to seen how effectively the XPB sealed off hole, not one drop of water out of the hole. I guess the water in the bottle was compressed to some insignificant degree.

Relying upon my memory, which can be 'iffy' at times, doesn't a bullet need about 180fps-230fps in order to puncture skin???

I think my German Shepherd has given me larger bruises than this XPB would have caused after exiting water bags. But, since bruising was your idea, would you like to send me some of your skin for testing?

Bob
Nope, don't want to volunteer for your bullet backstop either, but if it won't tear the plastic on a milk jug, I doubt it does little more than bruise skin. Ithink penetration in skin, or any soft medium is a product of dia, mass & minimum vel. A 147gr/9mm bullet going 200fps is more likely to penetrate than a 185gr/45 IMO.
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Old 10-07-2010, 15:43   #16
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Relying upon my memory, which can be 'iffy' at times, doesn't a bullet need about 180fps-230fps in order to puncture skin???


Bob
Bob,

According to Professor of Mechanical and Aerospace Engineering Caroll E. Peters of the University of Tennessee, the following algebraic expression...

V(fps) = 187 x <SUP>3</SUP>[(Din x 25.4)/6.00]

...will provide an acceptable penetration threshold velocity (VT) for a bullet of a given diameter.

You are, no doubt, already familiar with D. McPherson's VT equation as well.
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Old 10-07-2010, 23:01   #17
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Bob,

According to Professor of Mechanical and Aerospace Engineering Caroll E. Peters of the University of Tennessee, the following algebraic expression...

V(fps) = 187 x <SUP>3</SUP>[(Din x 25.4)/6.00]

...will provide an acceptable penetration threshold velocity (VT) for a bullet of a given diameter.

You are, no doubt, already familiar with D. McPherson's VT equation as well.
At least this is one of the easier formulas you've shared with me.

Bob
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Old 10-08-2010, 17:22   #18
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At least this is one of the easier formulas you've shared with me.

Bob
Oh, Bob....

While I do delight in confounding you endlessly , I find it the humane thing to throw ya a bone every once in a while. Stoking the fire, as it were.

I can zip the full .pdf to you if you wanna have a look at it. It is a neat and rather concise model based upon and improving the work (penetration mechanics) of Poncelet (1788-1867).

Shoot me an e-mail if you are interested. I am always looking for another avenue through which to pick upon you.
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Old 10-08-2010, 17:47   #19
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Oh, Bob....

While I do delight in confounding you endlessly , I find it the humane thing to throw ya a bone every once in a while. Stoking the fire, as it were.

I can zip the full .pdf to you if you wanna have a look at it. It is a neat and rather concise model based upon and improving the work (penetration mechanics) of Poncelet (1788-1867).

Shoot me an e-mail if you are interested. I am always looking for another avenue through which to pick upon you.
Just when I was thinking about invitin' you and the family for a Southwestern style BBQ over mesquite.

I wouldn't mind lookin' over what ole Ponce wrote, maybe I'll even catch up with some modern research.

While looking over some .327 Fed mag data, came across some of your 'work':

Quote:
Speer .327 Federal Magnum 115 gr. Gold Dot JHP

Impact Velocity: 1381 fps
Recovered weight: 114.2 grains
Recovered average diameter: 0.546 inch

Cavitation Boundary (Vc) = 419.069 feet per second
Permanent Wound Cavity Mass (Mw) = 38.122 grams (1.345 ounces)
Penetration Depth (Xcm) = 34.991 cm (13.776 inches)

Gelatin-to-water penetration ratio: 1 : 2.25
Out of all the water bag testing we did, would you consider this ratio to be 'mean' or 'average'?

Bob
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Old 10-09-2010, 14:10   #20
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Just when I was thinking about invitin' you and the family for a Southwestern style BBQ over mesquite.

I wouldn't mind lookin' over what ole Ponce wrote, maybe I'll even catch up with some modern research.

While looking over some .327 Fed mag data, came across some of your 'work':



Out of all the water bag testing we did, would you consider this ratio to be 'mean' or 'average'?

Bob
I'd call the ratio "average" and the performance of that hot little .32 "mean".

E-mail's on the way.
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