First thing we need to realize is the fact that there is a definitive difference between the guns you have access to, and what these companies are making for the government contracts they are filling. In many cases, such as the Beretta M9 used by the military, the technology has seen little to no improvement from the original contract specs. The 92FS on the other hand, has seen all the technological updates, resulting in the pistol being able to last even longer than its military counterpart. And also, you might notice that the components and parts on the civilian M9 are not the same as the ones used by the military. It has the same parts as the 92FS, which means that it is far from being a real M9. Plus, the government contracts are very specific with strict requirements not put in regular production guns, like testing the action with proof loads and scanning the metal for defects.
This pattern is the same for pretty much all manufacturers, and usually means that the springs are tighter, night sights are standard, and some parts are reinforced for longer life. Some manufacturers like H&K seem to produce all their pistols to the same specs, no matter if it is for a government contract or not. The USP being the exception for the German military. The P8 was made just to fill the niche of the German military, who wanted a different safety mechanism style and standard rifling. But most of the time, like in my old USP, the entire pistol was the same as one off the shelf, even though it was a pistol made for a Washington State Agency. That being said, it is common for agencies to want more, which would mean night sights, and a different finish.
For the most part, the pistols you are getting are not going to be the same as the ones that these federal agencies get. Sig, Beretta, and Glock are some of the top companies in the US for contracts with the government, and they have very different specs for almost everything from springs to finishes. Don't think that you are getting a genuine piece of hardware that is being used by these government agencies today, because really, you are not going to.