not a scrap build, but cool enough to mention. the semi-suomi in the pix is various and sundry suomi parts mated to a complete tec-9 style (KG99) closed bolt upper bought as spare parts. this gun runs, but needs a little adjustment to the ejector to get the 100% rating.
the tec barrel is cut off and bored out to accept a weld in of the suomi barrel, which is extended with a same OD thinwall tube. the front of the receiver is welded to a short piece of conduit which is then welded to a standard suomi shroud to get 16"+ from breech face to front of muzzle attachment. the loose FCG parts, after much pulling of hair, are housed in a drop in FCG pack. this pack slips into a housing which is welded to the receiver tube and held in place with (4) 10-32 allen head bolts.
the suomi magwell parts are welded to the receiver tube, and hold either a drum or a stick. the stick needed a small tab welded to front to limit insertion, and the bottom of bolt would have to be shaved to work with the single feed position drum. someday...
the magwell parts installation pushed the FCG assy back about 1/8", so the ejector is a little too far back. fired with a dry tube, ejection is 90%. WD 40 in the tube speeds the bolt up so that the ejected case is often caught by the bolt coming home on the next round, and we get stoppage. building up the front of the sheet metal ejector with a piece of cut nail and some silver solder to get earlier ejection seems a simple enough fix, or i could cut a new one from some harder steel. in future builds this will not be the case. i will be more clever and set the mag well correctly.
4 similar uppers available (AB10 and AP9) are slated for a yugo model 49 conversion using PPSH parts in 762X25, a wood stocked version of this poor creature in 9x19 that should fool the average joe, and god knows what else. the design deviation they will all suffer is that the distance from FCG to mag must be minimised, as the uppers are set up this way. good enough. it keeps the OAL down to about 25 with wire stock compressed, and 32 with wood stocks. perhaps a 762X25 pistol similar to the original application, but using pps43 mags.
of note, the AP9 parts sets are more easily adaptable, as they have all FCG parts in a trigger pack, while the AB10 and KG99 have them loose. these kits came from gunbroker. there is a seller of police demils on GB who has them from time to time.