To this day, we have still not matched the small arms advancements the Germans did during WWII. I have numerous WWII-era German firearms in the reference collection that I regularly use as basis for product development. The Germans had the production processes down and set the standards for features such as quick-change barrels, sub-machine guns, and interchangeable parts. The similarities between the Sturmgewehr and the SCAR rifles says much about German technology during WWII and no one still has a quick-change barrel as good as the MG-34 or MG42.
There is one MP-43 in the rack below amongst the other MP-44's
Here are some Yugoslavian paratroopers armed with StG-44's. They were issuing them up into the 70's, and I have a buddy who was a weapons inspector in Bosnia, Croatia, and Serbia that said they'd find bunkers with racks of StG-44's (and Thompsons too).