AWB317:
First, let me say "welcome to the Dark Side!" :-)
Debate swirls around the actual origin and meaning of the name "Krinkov" (of which "Krink" is an abbreviation), but that is the generic term for the AKSU family of weapons. Basically it's an AK rifle chopped down to SMG dimensions, but retaining the assault rifle caliber. Primarily of Russian or Bulgarian manufacture, with many variations in existence (stamped vs milled receiver, solid stock/underfolder/sidefolder, 5.45/5.56/7.62.
Several other nations have fielded "Krinkov-type" short AKs (Romania, Yugoslavia and Poland come to mind), but these differ significantly from the Russian/Bulgarian pattern.
Most everyone who owns a Krink in the States has had it built up on a host receiver, using a Bulgarian parts kit. These can be post-ban guns built on virgin receivers, or a rebuild of a pre-ban AK. Some folks register their Krink builds as short-barreled rifles, in order to avoid the need for a barrel extension.
Of course, there are some "post sample" select-fire AKSUs and AKS-74Us that are owned by Class III dealers/mfrs, and some individuals who have had their registered AK machine guns rebuilt into the Krink configuration.
I'm sure the usual suspects will be along shortly, with gobs more info and pics.