Should look at a couple of other places, too: France and Belgium.
With the German near-monopoly on international arms sales quashed by Versailes, FN in Belgium became much more important. The Belgians had a patent agreement with Mauser, so what they did was legal and paid for. The Czechs simply took all that fine German equipment they were given and set up in business, starting with the Model 23 Mauser, followed swiftly by the VZ-24..... which was almost a duplicate of FN's Mle. 24. These two plants supplied much of the worldwide rearmament in the 1920s and 1930s.
The Czechs developed what would become the BREN GUN and the BESA tank MG, also built zillions of them on contract for anyone with the cash, as the ZB-26 and/or ZB-30.... which became standard German weapons in 1938, of course.
FN made Mauser rifles and also had a working agreement with Browning, so they were able to build recoil-operated Browning MGs and a modified BAR for anyone who wanted the things. And they did.
France developed 2 new cartridges and new rifles and MGs both in the 1920s, then scrapped the 7.5x59 because it was much too easy to slip in a 7.92x57 German round and wreck your gun... so they shortened the thing a few millimetres to the 7.5x54 which they are still making and using. It went into new LMGs (Model 29, eg), into special 'fortress' MGs and into a variety of new rifles, of which the best was/is the MAS 36. A whole pile of older rifles (Lebels, Berthiers) were also converted to handle the new round.
Belgium even came up with a 7.92x57 conversion of the P-'14/US M1917 rifles. Don't know if it was ever made in numbers, but there is one in the Pattern Room collection. Nice.
But the Germans were the big machine-gun developers and they didn't, legally, have the capacity to make a machine-gun, so they stuck with the few old Maxims left over from the Great War and started development from the few later-type guns from the end of the War, coming up with what became the MG-13, built from 1918 Bergmann guns and later sold to Portugal, which used them up into the 1960s. Several boxcars of DWM research papers had gone to Holland and to Switzerland before the IAACC guys got to the factory, so the knowledge was saved at least. Development proceeded quietly on the Rheinmetall MGs (MG-29, MG-30: saw one in 'Star Wars', BTW) which were developed by Mauser into the MG-34. Basic design for the MG-42 came out of Poland, fellow named Stecke. FG-42 was a product-improved Lewis with a Johnson trigger assembly and magazine; it was united with the MG-42 feed assembly and became the M-60, so the basic gun came back to the US 46 years after its 1911 rejection, all spiffy and 'new'.
There has been nothing really NEW since 1945, although there has been a LOT of DEVELOPMENT.
Still lotsa countries left, but my fingers are sore from this fordammet laptop keyboard.
Have funs!
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