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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;

Caliber Corner

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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Old 10-09-2010, 23:21   #21
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I'd call the ratio "average" and the performance of that hot little .32 "mean".

E-mail's on the way.
Average, got it.

Bob
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Old 10-10-2010, 16:38   #22
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With different bullets/velocities, and containers (bags), couldn't some of the penetration really be the result of water being thrown out of the way of the bullet? Shoot into a large, strong, container of water and the water will have no where to go, so the bullet must drive through it. Shoot into a bag and the bag may empty out before the bullet finishes going through it, meaning some of the bullets path may be through essentially air. Fast bullets may be more prone to this. Gel and wetpack don't move out of the way, so the comparison may not be valid.
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Old 10-10-2010, 19:53   #23
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With different bullets/velocities, and containers (bags), couldn't some of the penetration really be the result of water being thrown out of the way of the bullet? Shoot into a large, strong, container of water and the water will have no where to go, so the bullet must drive through it. Shoot into a bag and the bag may empty out before the bullet finishes going through it, meaning some of the bullets path may be through essentially air. Fast bullets may be more prone to this. Gel and wetpack don't move out of the way, so the comparison may not be valid.
All kinds of interesting things can happen when doing bullet/water tests; sometimes there is enough water pressure to actually 'bounce' (change direction) the bullet;

Caliber Corner

9mm/147gr (IIRC) bullet started out parallel with the cradle, dramatically bounced upward and to the left;

Caliber Corner

This 125gr Gold Dot in the mid 1600s blew up this gallon bottle; probably didn't slow down much as this Christmas Day pic shows;

Caliber Corner

Sometmies solid bases aren't as solid as we think as this .38Super/147gr test result shows after penetrating a 1/10" hard steel plate;

Caliber Corner

If water pressure wasn't enough in blowing through the 1/2" pressed wood base in the above pic, this .44mag/210gr Silvertip/1570fps yielded the most violent test I've done;

Caliber Corner

Five water bottles were placed inside if those heavy railroad ties.

I don't know how long it took for that Silvertip to travel through about 12" of water, but #3 bottle wasn't touched . . . bottles #4 and #5 also exploded with the ST coming to rest against the backstop railroad tie.

I've read about tests that have had 1" thick planks supporting gel blocks splitting.

You may want to research how far bullets travel when fired underwater.

Bob
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Old 10-10-2010, 20:34   #24
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When I have done my own testing with gel and water, I had a .45 load (RA45TP) that penetrated 16" in gel, but only went through 3 jugs, which is ~18" of water, which is way off the 2.25:1 ratio. But on the other hand, I have had a 9mm load (9BPLE) that only went 9 inches in gel, but went through 5 jugs of water.

Bullets are funny, because they dont always do the same thing everytime either. I went through almost a whole box of RA40T, RA40TA, Federal 180 gr HST and Federal 165 gr HST, and the testing was over a month long time frame. Some penetrated deeper than others, some expanded more, and I am speaking about bullets within the same ammunition group, not between the different designs and weights.

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