At times I wonder if the FSB(?) are the ones getting first dibs on good hardware other than the Spetsnaz.
You are correct. FSB are often self-supported in regards on buying equipment. They buy whatever tech they need from their own funds (and often from individual operator pockets). Hence why they ofter carry around Glocks, M4, MP7, Hk G36k and such because their armament are not strictly regulated. (i.e. whatever gets the job done right) Spetznaz on the other hand is a direct branch of the military that are being sponsored by government-issue weaponry and have a strict mandate regulations on equipment.
Or something like that. If anything is still unclear it's probably due to my rusty english, ask questions and I will try to answer to best of my abilities.