Germany started the war with bolt guns and then developed a semi-automatic rifle, the Gewehr 41, that was, as Dunlap puts it, “not a production-line weapon.” They also developed some submachine guns:
The submachine gun appealed to the German mind as a fine weapon, though they fooled around and never put out any one model in any quantity excepting the Schmeisser Models 38 and 40. This is the familiar machine pistol, the all-metal and plastic “burp” gun with the folding stock and Buck Rogers styling. Originally intended as an in-between weapon, to replace pistols and rifles in the hands of special units such as paratroopers, motorcycle and bicycle troops, tank men and special guards, it became so popular that it seemed just about every fourth Kraut had one. The other three? One had a Mauser with a telescopic sight; one had a Spandau all to himself, with unlimited ammunition; and the fourth man had an 88. If you think I am exaggerating much, just ask the nearest guy who lived through Italy. Jerry really had firepower.

The MP 38 and MP 40 were known as Schmeissers — to us, that is:
The MP 40 was often called the “Schmeisser” by the Allies, after the weapon designer Hugo Schmeisser. Schmeisser had designed the MP 18, which was the first mass-produced submachine gun in the world, and carried some resemblance to the MP 40. He did not, however, have anything to do with the design or development of the MP 40, although he held a patent on the magazine.
A Spandau was any German machine gun:
The [MG 42] (like the MG 34) was sometimes called “Spandau” by British troops, a traditional generic term for all German machine guns, left over from the famous Allied nickname for the MG 08 Maxim-derivative used by German forces during World War I and derived from its manufacturer’s plates noting the city of Spandau where some were produced.
An 88 was an 8.8 cm Flak gun:
Paul Fussell wrote that American troops “knew that the greatest single weapon of the war, the atomic bomb excepted, was the German 88 mm flat-trajectory gun, which brought down thousands of bombers and tens of thousands of soldiers. The Allies had nothing as good”. The 88 mm was used in two main roles: as a mobile heavy anti-aircraft and as an anti-tank gun. Other uses included firing in support of the troops at the front; and as a more static anti-aircraft gun for home defence.
Dunlap had a few things to say about submachine guns:
The little squirt gun, which is the only German gun to our notion that deserves their name of machine pistol rather than be known as a machine carbine or submachine gun, has been ridiculed by a lot of people who should know better. Sure, it is no long-range gun and it shoots too fast and it looks funny, but it killed a lot of people just the same. There is nothing amusing about the way one sounds when the proprietor holds the trigger down a second or two.
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The M40 was simply the 38 with all possible machining and manufacturing operations omitted or simplified.
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The Jerries had trouble; a lot of them managed to snag that handle on the back of the belt or the shirt or bandolier, with the result that it pulled out of the safety notch, the bolt flipped forward, scooped up a cartridge on the way and finished by shooting our superman in the leg or the seat of the pants, depending on how he had hung the gun on himself.
It was even rumored that sometimes the bolt received a little unofficial help. In a lot of spots a nice clean 9mm hole through the calf of the leg or a gouge across the fanny can look like a damned good ticket out of a front line hole.