A gel expert explains

Kleanbore said:

Without specifying a testing regime, one cannot issue a performance requirement--and the FBI has not issued a minimum penetration requirement for soft tissue.

Capisce?

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I am well aware that ammunition testing practices would be highly impractical if tissue was used instead of 10% standard ordnance gel; however, I was simply quoting FBI's Urey Patrick statement (in "Handgun Wounding Factors and Effectiveness") that " a handgun bullet MUST (his capitalization for emphasis) reliably penetrate 12" of SOFT TISSUE (my capitalization emphasis)."
Si, capisco tutto!

d2wing said:

I have withdrawn my comment and apologize for it. I am a cranky old guy some days.

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No need to apologize to me; I agreed with your post about irrelevance of bulk modulus and sonic velocity (apart from being variables in a function for density which is by itself an important function in bullet penetration). Actually two fluids can have very similar density but different bulk moduli and sonic velocities -- it's density that matters in bullet penetration. Incidentally, your comments about irrelevancy of sonic velocity in a body, compared to sonic velocity in a homogeneous gel, is correct as well; the fact that sonic velocity varies significantly over short distances in a body makes ultrasound diagnostics possible.

Kleanbore said:

You did quote that statement later, but earlier, you mischaracterized it as the FBI requirement.

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Well, it certainly seems to me that if, according to referenced FBI's Urey Patrick's statement that a handgun bullet MUST reliably penetrate 12" of soft tissue and that up to 18" penetration is better, then that is a FBI requirement for bullet penetration in soft tissue, not a mere suggestion. From Webster: must -- to be bound or obliged to by imperative requirement.

Kleanbore said:

No.

Special Agent Patrick wrote that in the report, but it was never issued as a requirement, nor would it have been reasonably possible to determine whether or not ammunition actually meets any such "requirement".

Both would be fundamental.

The requirements involve specific passing specific testing protocols in ballistic gel.

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FBI's Patrick was part of the team that analyzed '86 Miami event and his work resulted in specifications for .40 S&W and implementation of the revolutionary FBI ammunition test series. He also created FBI basic training curriculum, as well as firearms training that are included in all Bureau training. He completed a scientific study in the issue of how bullets kill, the results of which were the basis of the FBI ammunition test protocols and used to define bullet performance parameters for law enforcement ammunition analysis and procurement.
Thus when Urey Patrick, based on the above, in his referenced paper, says that a bullet must reliably penetrate 12" in soft tissue and up to 18" penetration is better, it doesn't at all seem that it's "off-base" to quote the above as the FBI's minimum penetration requirement in soft tissue. However, of course, I did not state, imply, or suggest that 12" minimum penetration in soft tissue is the only terminal ballistics requirement.

Also, from MacPherson ("Bullet Penetration" book, 1994):" The minimum acceptable penetration in soft tissue to ensure reaching and traversing vital organs in typical trajectories in most human bodies was discussed and accepted as 12" after the first Wound Ballistics Workshop at the FBI Academy in September 1987; this conclusion was discussed and confirmed without controversy at the Wound Ballistics Seminar at the same location in January 1993."