T2C–what type of projectile and loading? Were the bullets tested in bare gel or in 4LD or heavy clothing?
Shots into bare gel only tell us the maximum expansion that is possible.
A more realistic assessment is the IWBA 4 layer denim test or the FBI heavy clothing test. The four layer denim test is NOT designed to simulate any type of clothing–it is simply an engineering test to assess the ability of a handgun projectile to resist plugging and robustly expand. FWIW, one of the senior engineers at a very respected ammunition manufacturer has commented that handgun bullets that do well in 4 layer denim testing have invariably worked well in actual officer involved shooting incidents. It has been my experience that most handgun bullets recovered from human tissue in surgery or at autopsy tend to look like those same type of projectiles after 4LD testing.
As many folks know, in the wake of the 1986 FBI incident in Miami, LE began to investigate what criteria should be used to optimize handgun ammunition terminal performance. To help guide that development, the FBI held a series of wound ballistic workshops in 1987 through 1993, inviting leading experts to address the topic. These FBI workshops lead to the establishment of the FBI ammunition testing guidelines—this was good for the public, LE, and ammunition vendors, as it articulated a clear set of performance criteria resulting in more effective and safer ammunition. Ammunition engineers were able to use the new test protocol as a metric to guide bullet design. The first generation of handgun ammunition designed to meet the new FBI terminal performance guidelines included the Federal Hydrashok, Hornady XTP, Remington Golden Saber, first generation Speer Gold Dot, and Winchester Black Talon. These bullets all offered improved penetration to reach the desired 12-18” guidelines and somewhat better intermediate barrier performance, however, they still demonstrated inconsistent terminal performance under some conditions, particularly with heavy clothing and through automobile windshields. As a result, the IWBA began a series of tests to determine what needed to be done—this data, along with suggested engineering changes and test protocols, particularly the 4 layer denim test, was shared with industry. By 1997, many munitions engineers began incorporating these updates into LE handgun ammunition, eventually leading to improved loads like the current Barnes Tac-XP, Federal HST and Tactical, Remington bonded Golden Saber, current generation Speer Gold Dot, Winchester Ranger Talon, and Winchester Bonded. The results of the IWBA experiments, corrective recommendations, and engineering test protocls were published by the IWBA in an article by Duncan MacPherson (MacPherson D: “Improved Handgun Ammunition”. Wound Ballistics Review. 3 (3):12-21, 1998). This, along with Duncan’s book (MacPherson D: Bullet Penetration: Modeling the Dynamics and the Incapacitation Resulting from Wound Trauma. Ballistic Publications, El Segundo, CA, 1994. ISBN 0-9643577-0-4), remain the best sources of information on this subject.