The .40 was the making of the agency and I believe Winchester after the Miami shootout fiasco. If you don't know this story Google it. Initially they started with the 10mm, but some of the boy's couldn't control the firearm and more and more women were working in the field. The 10mm has a good sized grip. So, they came up with the 40 S&W. Some refer to the .40 as the Short & Weak. as in the smaller than 10mm round.
As far as the ammo goes, I know Winchester got a big contract with them, but it could be for practice ammo.
It's probably a 165 gr. bullet, perhaps Gold Dot or Ranger T's