.45 Autos were authorized for agents almost immediately after the 4/11/86 shootout, and at least one .45 has been on the approved list since. I've carried a personally owned, Bureau approved Sig P220 for over 16 years. Ammo was originally the 185 grain Silvertip, then the 230 grain Hydra-Shok, and now its the 230 Golden Saber.
Field agents can carry the Glock 21, and Sig 220s like mine are grandfathered in, though no longer on the approved list. SWAT agents are issued a Springfield 1911, and the HRT guys carry the hi-cap .45 ACP.
There is a lot of internet ******** out there about 4/11/86 in general and the 10mm in particular. The Bu did extensive ammunition tests based on what the Bureau wanted a handgun round to do. To their immense credit, they opened the testing up to all commercially available rounds, including the nearly dead 10mm. The testers found the 180/950 round did everything they wanted it to do. The fact that the full power 10 was also available was considered a bonus, much in the way .38 Specials were standard, but .357 Magnum rounds were available as needed for specific requirements.
Full power 10mm was never issued, so the idea that agents couldn't handle the recoil is internet hooey. The 1076 was a very well liked pistol and very few agents who had one wanted to give it up. As recently as three years ago I was qualifying an agent who hung onto his despite repeated efforts to recall it to the gun vault. They finally threatened to dock his availability pay and he returned it.
The testers looked at our shootings and decided they wanted a deeper penetrating 9mm, hence the 147 grain - first the HS, now a Gold Dot. Since we don't issue ammo to other departments, nobody out there was required to follow suit. The 147s have performed as expected, though not that many agents carry 9mms anymore. I know a guy who has killed two bad guys with two rounds of 147 grain 9mm Hydra-Shok. He has no complaints.
The 10mm 180/950 led directly to the development of the .40 S&W, which is the current bureau issue in a 165 grain Gold Dot.
The 10mm is still in service with the FBI, in a 190 grain loading. We use it in these:
