@drgrant Mike, this is my last attempt discussing the development of the .40 S&W (at least with you). Many years have passed since you and I read about its development, so I'm not surprised about the comment that the FBI and S&W intentionally downsized the 10mm to make the .40. However, this comment didn't sit well with me because it didn't comport with what I read and learned about the matter years ago. I also added more citations in which you can say they suck, but they do prove my side of the story. In addition, you can tell me that I'm still spinning the facts, but that would be factually incorrect on your behalf. Subsequently, I researched this issue again to
relearn the factual historical development of the .40 S&W as I remembered it (but had forgotten the details).
After the 1986 FBI shootout in Miami where two agents were killed, the FBI determined that the 9mm and .38 Special the agents used were subpar in performance. When The FBI began their tests, they focused first on the 9mm and .45 to see if they could improve their performance using existing technology. While doing this, it was also decided to look into a .40 caliber intermediate round between the 9mm and the .45.
It just so happened that another FBI agent had already started working with the 10mm using his personally owned Colt Delta Elite 10mm, so it was decided to add his 10mm testing to that of the 9mm and .45 test protocols. In addition, the FBI also tested the 10mm in a Thompson Model 28 submachine gun. Eventually, the FBI adopted the Model 1076 in 1990, a short-barreled version of the Model 1026. Prior to this though, the FBI found that the commercial 10mm load during the testing didn't perform well in meeting their test protocols. The bullets simply failed to expand and penetrate consistently at the higher velocities. Therefore, they experimented with the 10mm until they reached a velocity between 900 to 1,000 fps, where the bullet performed consistently and was subsequently referred to as the FBI Lite load at 950 fps.
At the same time, there wasn't a suitable gun that they could use it in, which is why they used a 6" barrel. The other reason for using the 6" barrel was because it was required by SAAMI specs for the 10mm and .45 ACP at that time (this is where the 6" barrel comes into play in the 1989 FBI report). Just because the testing required a 6" SAAMI-spec barrel, they had no intention of using a gun with a 6" barrel.
The FBI then asked S&W to design a gun using the frame of the S&W Model 4506 for their 10mm Lite load. Simultaneously, S&W and Winchester had already been working secretly on a .40 caliber round based on the Centimeter round (.401) that had been designed years earlier by Paul Liebenberg from S. Africa. Liebenberg designed the round so that it could compete in IPSC Major Caliber competition. The resulting Centimeter round ended up being a success and outperformed the .38 Super Colt, which was the "go to" round in use at that time. The Centimeter cartridge had an
overall length and a
case length that was
already shorter than the 10mm round.
Paul Liebenberg, who worked for Pachmeyer, left and started his own company to work further on the Centimeter cartridge development. He teamed up with Tom Campbell and they both went to S&W in an attempt to get them interested in it. Eventually, S&W took an interest in the Centimeter round and the president of S&W, Steve Melvin, asked Liebenberg if he could convert their new 3rd generation Model 5906s to use the Centimeter round. During the testing of the Centimeter round, S&W realized that they could get the same performance out of the shorter cased round to meet the FBI Lite load specs. And that was the genesis of the .40 S&W! It had nothing to do with the FBI or S&W intentionally downsizing the 10mm, but it's your decision to keep using that incorrect information and to tell me that I'm spinning the facts
10mm Auto - Wikipedia
.40 S&W - Wikipedia
In Praise of the [Clearly Superior] .40 S&W Cartridge - The Truth About Guns
Welcome to Pistol Dynamics
https://www.ncjrs.gov/pdffiles1/Digitization/122334NCJRS.pdf
A History of FBI Handguns