Comments by "geodkyt" (@geodkyt) on "Book Review: Vickers Guide H&K Volume 2 (SMG & PDW)" video.
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HK didn't think it was necessary (in longarms, most of the guns that had automatic bolt hold open were derived from.clip loading guns, and almost no SMGs had the featyre) and would unnecessarily complicate gun (I know, German engineers worrying about complexity 😂 ), most of their customers agreed, and later retrofitting it into the mechanism would have required new magazines and receivers when they already had a very popular design that was selling all they could make. Also, the CETME all of the HK roller delayed long guns were derived from (and the StG45 the CETME was derived from) didn't have it.
Now, when enough money was on the line (the FBI saying, "We'd love a 10mm MP5, but we insist on a bolt hold open... Colt is willing to accommodate us with an AR15 SMG...", or HK hoping to land a "NATO de facto standard rifle" winner and developed the G41 just as the the NATO ammo trials looked set on 5.56, or even earlier when trying to sell the HK21 to the US Army), HK was more than willing to oblige.
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