The parts kits for the stg44 used to be available in huge numbers back in the late 90s and early 00s. You could purchase the parts kits for a little over 200 dollars. The american company that made the stg44 replica used parts kits built on their own receiver.
There were thousands of stg44s discovered in an arsenal in Syria by rebels only a few months back that are seeing action for the first time.
Even in Africa stg44s have turned up on occasion in the hands of militants.
Personally the rebels should sell those stg44s on the international market and buy 30 times their numbers in ak47s.
There were a huge number of these guns built by the end of ww2. The problem was getting them to the troops with sufficient ammunition. By that time transportation and fuel supplies were so suppressed that nothing could leave the factories and get to the troops (which suprisingly kept going until the surrender). Command and control was in tatters, you would find units all mixed together with different kinds of guns and no ammo while other units had ammo but no guns. Many armored vehicles were simply parked at tactical strongpoints with no fuel turning them into makeshift bunkers.
Sorry for the little history lesson. Only pointing out that there were huge numbers of the guns built considering the short period of time they were in production.