Thoughts on ballistic measurement [Archive] - Glock Talk


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04-01-2010, 10:43
Mr. Ayoob: First, I've been reading your writing for most of my life and I would like to thank you for letting me benefit from your work and I would also like to thank you for responding to us personally on this forum.

I'd like to know what you think the more valid techniques for measuring ballistic effectiveness are. I think opinions vary widely on this. On the one hand, I have the three Marshall and Sanow books and I frequently reference the one shot stopping percentages they list. On the other hand, a trusted shooting instructor is a retired SWAT guy and he prefers to rely more on gelatin tests.

I would appreciate any feedback that you might have on this subject.

Mas Ayoob
04-01-2010, 13:19
"Stopping Power" is a way more complicated topic than it seems, as witness the huge amount of bandwidth it has sucked up over the years in GT's own Caliber Corner. Because life and death are involved, some folks treat it as something close to a religion, and even become "crusaders" for their "ballistic belief system."

Personally, I think each side holds a piece of this very complicated puzzle. I am partial to the collected street results, and keep in contact with police firearms trainers around the country through organizations such as ILEETA to see what's working best "on the street." The collective feedback from there tends to validate Marshall's and Sanow's recommendations. However, both Marshall and Sanow also use ballistic gelatin in their testing and evaluation.

Dr. Gary Roberts, perhaps the leading proponent on the other side of the debate, obviously relies heavily on FBI/IWBA protocol gelatin testing, but also makes a point of gathering feedback from police and military users. So, both "sides of the debate" obviously see value in both lab testing and monitoring street results.

If doubt about which theory is right creates a crisis of confidence, you can just buy ammunition that both sides hold in high regard. That includes the 158 grain lead semiwadcutter hollow point +P in .38 Special for example, the 230 grain jacketed hollow point in .45 ACP, and the 180 grain subsonic JHP in .40 S&W. Both factions seem to feel that modern high-tech bullets have performance advantages over conventional "old school" JHPs.


04-01-2010, 14:40
Thanks. I tend to straddle the fence on this and I figure both fields have plenty to offer.

One area where I am left wanting more information is the .357 sig. When Marshall and Sanow released Stopping Power in 2001, their data for the .357 sig was based on less than 70 shootings. I would think with ten years more data and a lot more trained law enforcement personnel using the round that more data would be available. I also would think that the first shot stopping percentage may have changed (potentially proving that the round does or does not approximate the capabilities of the .357 magnum).

Do you know of any publicly viewable "collected street results" from organizations such as ILEETA etc which use the first shot stopping percentages?

Mas Ayoob
04-01-2010, 17:19
ILEETA itself does not keep track of equipment/ammunition performance, but its thousands of members from departments all over the country and in other countries are a treasure trove of information.

I don't know of any department that keeps track by one-shot stop percentages. However, those with the .357 SIG seem to be extremely happy with it. Most of the agencies reporting high success rates are using 125 grain Gold Dot, including VA State Police, NM state troopers, Texas DPS, and Richmond, VA PD.