Baseless
No they don't. You're parroting a myth.
The FBI only ever issued their 10mm with a downloaded round, a 180-gr Sierra bullet at 950 fps (vice Col Cooper's 200-grain bullet at 1,200 fps), often called the "FBI 10mm Lite" load. Before they ever issued that first S&W 1076 to their agents the FBI did extensive ballistic testing on the cartridge and determined their goals could be met with the FBI Lite load, which also would be cheaper to manufacture and put less wear-and-tear on the firearms.
The FBI NEVER ISSUED a full-house 10mm Auto round, only the FBI 10mm Lite.
The FBI Lite load left so much unused case capacity that S&W sensed the business opportunity and approached the FBI with the idea of a 10mm cartridge shortened by 0.142" (allowing for a substantially less girthy grip) but loaded with THE EXACT SAME PROJECTILE AND TO THE EXACT SAME MUZZLE VELOCITY as the FBI 10mm Lite. And they called it the .40 S&W.
Which means the FBI's issue .40 S&W load was ballistically identical to their issue 10mm Auto load. Which further means it killed just as dead.
The story that the FBI ditched the 10mm because their agents weren't manly enough to shoot it is a complete fabrication still being perpetuated 30+ years later by people who would rather sling baseless insults at the FBI look into the facts of the story.
Baseless
If the FBI intended from the start to use a 180 grain bullet at 950 fps, they would have stayed with the .45 ACP. There were plenty of handguns already in that caliber. Their overseas counterparts in government and law enforcement overseas were already using 45 ACP in handguns from Beretta, H&K, FN, and Sig Sauer since the 1950s.
That the FBI went to the 10mm and later downgraded it points to problems with the agents handling the 10mm.
The FBI Lite load left so much unused case capacity that S&W sensed the business opportunity and approached the FBI with the idea of a 10mm cartridge shortened by 0.142" (allowing for a substantially less girthy grip)
The claim that S&W approached the Feds and said, "Since the cartridge uses less powder, we can shorten it to save space in your guns." is far less believable than the FBI seeking a handgun that agents with smaller hands could use. Instead of making it obvious that they were issuing smaller guns to female agents and having male agents opt for .45 ACP, they would downgrade the weapon for everyone and claim it was intentional. That's exactly how government DEI works.
Also, thanks for making my case for me: Before they ever issued that first S&W 1076 to their agents the FBI did extensive ballistic testing on the cartridge and determined their goals could be met with the FBI Lite load, which also would be cheaper to manufacture and put less wear-and-tear on the firearms.
I stand by my comment.