http://www.backwoodshome.com/articles2/ayoob93.html:"This resulted in the FBI Wound Ballistics Workshop of 1988 in Quantico, Virginia. Among those present were Dr. Martin Fackler, head of wound ballistics research for the US Army's medical training center, Letterman Institute. Fackler had developed an improved ballistic gelatin model that he had scientifically correlated to swine muscle tissue, which in turn is comparable to human muscle tissue. He hypothesized that wound depth was much more important than previously thought, and recommended ammunition that could send a bullet at least twelve inches into his ballistic gelatin."
"Ballistic Gelatin"(PDF). FirearmsID.com: An Introduction to Forensic Firearm Identification. 2006-10-16. Archived from the original(PDF) on 2006-05-11. Retrieved 2025-07-10.
"Ballistic Gelatin"(PDF). FirearmsID.com: An Introduction to Forensic Firearm Identification. 2006-10-16. Archived from the original(PDF) on 2006-05-11. Retrieved 2025-07-10.
