We regularly see the MP43/44/StG44 portrayed with an optical sight (a ZF-4). But was this really something that the German Army actually issued? Well, in a word…no.
The first iteration of the Sturmgewehr, the MKb-42(H), was designed to potentially fit a ZF-41 long eye relief optic on its rear sight tower. A few of these setups were made during testing, but he General Staff dislike the mount and wanted something more solid.
The next iteration was a test in September and October 1943 comparing the new ZF-4 optic on the MP43/1 and the G43. The same type of mount was used for both rifles, and the MP43/1 had a stamped mounting rail spot welded to the right side of its receiver. However, it performed quite poorly in testing – much worse than the G43. The MP43 accuracy was awful (about 11 MOA on average), the optic was useless in bursts, and the scope couldn’t hold zero during burst fire. A followup test was done in January with ten more Sturmgewehr, and the same basic results were found again. The stamped receiver of the Sturmgewehr was simply not a solid mount for an optic.
That was the end of any possibility for making the MP43 or its later iterations into a marksman’s rifle. A few later-war guns were fitted with the mounting rail, but most likely for use with the Vampir night vision system (which was a close range affair and didn’t require a very repeatable mount).