This guys explaination of gel results

[wrinkles]

I know that this isn't calibrated gel but this guy, to me, seems to be wrong. He's saying that the gel crack he's seeing is the HP petals cutting the gel. My understanding of Duncan McPherson's book is that the HP will not cut a hole the exact size of it's expanded diameter. Seems this guy is wrong or this gel stuff doesn't correlate well with tissue. Doc any advice?

Crap can't figure out how to imbed.

http://www.youtube.com/watch?feature...&v=LCb-knnGgeM

<iframe width="560" height="315" src="http://www.youtube.com/embed/LCb-knnGgeM" frameborder="0" allowfullscreen></iframe>

[S. Galbraith]

Gel was never meant to be a substitute for tissue. It is simply a media that has similar hydraulic properties to that of tissue, thus causing similar expansion levels. 12" of penetration in gel does not equal 12" of penetration through the human body. It is simply a repeatable, and measurable standard that was developed by field observations. A particular load is observed in the field either in OIS, cadaver, or animal shootings and it is then compared in gel to determine what is an ideal penetration standard.

[wrinkles]

I understand the penetration part but what about crush cavity. Like I said this guy is saying that the crush cavity is exacty the size of the HP expanded petals. in the area of 2-4" of penetration. According to what I've read the crush cavity is not 100% the size of the expanded HP.

[DocGKR]

From the looks of the video, he accurately described the permanent cuts caused by the expanded handgun JHP projectile as it cut its way through the block. The permanent wound track or crush cavity in living elastic tissue tends to shrink back a bit after bullet passage. The synthetic gel blocks are NOT living elastic tissue, nor have they been correlated with living tissue. Note that the synthetic gel blocks do NOT replicate TC very well, especially with rifle projectiles. The synthetic blocks seem to be adequate for looking at handgun projectile penetration depth and bullet deformation.

On the other hand, the IWBA published some of Gene Wolberg’s material from his study of San Diego PD officer involved shootings that compared bullet performance in calibrated 10% ordnance gelatin with the autopsy results using the same ammunition. When I last spoke with Mr. Wolberg in May of 2000, he had collected data on nearly 150 OIS incidents which showed the majority of the 9mm 147 gr bullets fired by officers had penetrated 13 to 15 inches and expanded between 0.60 to 0.62 inches in both human tissue and 10% ordnance gelatin. Several other agencies with strong, scientifically based ammunition terminal performance testing programs have conducted similar reviews of their shooting incidents with much the same results--there is an extremely strong correlation between properly conducted and interpreted 10% ordnance gelatin laboratory studies and the physiological effects of projectiles in actual shooting incidents.

[wrinkles]

So in the gel block those cuts that start at about 2" and go on for +-4" are actually produced in tissue. Since tissue is elastic those cuts would not be as large as the ones in the gel. The cuts are not 100% the diameter of the "clouded" part in the gel since each petal would cut an individual "slice" in the tissue cutting more of a star shaped wound.
Is this a correct assumption Doc?

Thanks for the info.

[DocGKR]

The bullet is slowly rotating in the tissue or gel block, thus creating the spiral shape as it cuts in a rotational manner after expanding in the first inch or two. Don't get too hung up on all this--handgun bullets poke holes. Nothing earth shattering.

[wrinkles]

Yea I get a bit obsessed some times.

I was discussing Duncan McPherson's book, the section about projectile shape and crush cavity size, with a friend. This came up after he said a .45 cal fmj will make a .45 caliber hole in tissue. He posted gel video and he was saying that the cuts in the gel are proof that the bullet is making a hole exactly the size of the diameter of the expanded petals.

Below is what I was posting.

.43 Sphere
.69 Round Nose
1.00 Cylinder
.66 Truncated Cone
.66 Semi-wadcutter
.63 45-degree half angle cone
.82 JHP

[DocGKR]

His comment does not account for tissue retraction...

[wrinkles]

Thanks Doc. My obsessive compulsive side is laid to rest.

[KlintonP]

.43 Sphere
.69 Round Nose
1.00 Cylinder
.66 Truncated Cone
.66 Semi-wadcutter
.63 45-degree half angle cone
.82 JHP

Now I'm confused. I always thought that since wadcutters were quite efficient at cutting tissue, they would leave a greater permanent wound cavity per caliber than any other non-expanding, non-fragmenting alternative. These numbers show a FMJ causing a larger permanent cavity than a WC, don't they?