I'm sorry but necromancer is my second name.
Shooting SMGs at distances longer than 50m were, at my time, only practiced at the police academy to learn that it is possible. Later the typical distances were 50 and 25m for the selective firing, down to 10m for the full auto parts of our practice.
I can only say I'm familiar with the MPl and the MP5A3 when talking about SMGs. The Walther has a lot of bugs build in by design. The iron sights, maybe, the open bolt, no. We had to practice a lot with both SMGs, I can not say that one was less accurate than the other one.
... they confound reflexive shooting at close-range targets ...
Think you mean quick instinctive, non-aimed shots. Please keep in mind that at the time our Manurhin MPl was "state of the art", we had to practice the (non-) aiming position from the hip...
And yes, the most of our firearms were "Made in France" since 1961 or 1963, I'm not sure about that.
The P1 first generation, The MPl/MPk, the Diana flare gun/tear gas launcher and the Mauser made MG3 were assembled and proofed by Manurhin (the MG42 was converted by them to 7.62x51 too).
Our G3 was really made in France by MAS in license. We still had US made weapons, the 81mm mortar and the 81mm Super Bazooka.
The martial law regulation "no German weapons" was disbanded in 1979 when the first P6 arrived. The teargas and the hand grenades (DM51) were never foreign "assembled" or "proofed" but officially made in Germany.
Sometimes in the mid seventies, the British Sector Commander Brigadier General (?) inspected the barracked special police of his sector.
With kindly permission by the Polizeihistorische Sammlung Berlin.