What? 10 MOA is a 10" group at 100yd if I’m not mistaken, and the MOA increases with more and more distance which means at 200yd it would be 20 MOA which is 20", which is roughly torso-sized. By 400yd, it’d be 40", or 3’4, which is more than 1m. You’d basically need two guys standing shoulder-to-shoulder and aiming right between them around the elbows/forearms in order to get a nearly-guaranteed hit on one of their torsos or groins or heads. That’s ludicrous. I myself have done some shooting with a mid-war M91/30 that had a replica PU scope mounted on it. At 200m (220yd) I could get multiple hits on an 8" (20cm) gong which is roughly the size of someone’s head, and that’s 4 MOA, and I was using steel-cased and laquor-coated ammo that was over half a century old. I’ve also personally received no formal training for marksmanship, only for safe firearms handling. I could also land hits on a torso-sized target at 300m (330yd) with ease.
Also, the No.4 Mk.I Lee Enfield has a maximum MOA out of the factory of something like 2.5 I think, and that was further improved with the post-war No.4 Mk.2 which was 2 MOA out of the factory or less and that’s with irons. Now, the Mauser Kar98k wasn’t quite as inherently accurate if memory serves, and they may not have even selected particular examples when mounting optics. With the Russians… perhaps for obvious reasons given their less-than-stellar QC, they specifically picked out Mosins that demonstrated impressive accuracy and gave THOSE scopes. They didn’t select any old M91/30, but the Germans did. I don’t know about what the Americans did in regards to putting optics on their M1903 rifles, but anyhow, I find your assertion that “Less than 10 MOA would be considered good on WWII era” to be a bit ridiculous, no offense.
To put this into perspective, SMGs are generally regarded as being effective out to about 150-200m. I think I recall seeing footage on YouTube of someone taking an MP5 out to 250yd, possibly even 300 and/or 350yd, and they were managing some hits… but that’s a post-war and closed-bolt SMG. We’re talking about WWII open-bolt SMGs and open-bolt is inherently less accurate than closed-bolt because JUST before the round is fired, the bolt in the firearm needs to slam forward. With closed-bolt, the only movement before the round is fired is the pulling of the trigger (which yes that can very much affect accuracy if you’re not doing it right) and then either the dropping of the striker or the swinging of the hammer, which is a small piece of metal, not a huge chunk of metal.
Anyhow, if SMGs are only effective out to 150-200m, if it can’t consistently hit a torso-sized target beyond 200m, THAT is roughly 10 MOA since beyond 200yd (190m or so) you’re looking at groupings of over 20", which is wider than the human torso/arms.
Meanwhile the AK-47/AKM is regarded as a firearm effective out to about 300-400m or so. It’s around 400-500m, if I’m not mistaken, when typical 7.62x39 falls from supersonic into subsonic which destabalizes the round and messes with accuracy. So, if a selected AK-47 or AKM in 7.62x39 can hit a torso-sized target at 400m but beyond that cannot consistently hit it, even under ideal conditions (I’m aware that some 7.62 AK rifles can, but I’m using this as an example) then that means that it’s probably around 4-5 MOA since beyond 400m the grouping is stretching beyond 16-20". Just how inaccurate do you think typical WWII bolt-actions are? Even in WWI, as I recall, Mk.III* Lee Enfields required a maximum MOA of about 3.5 I think, which if so, the worst possible Mk.III* out of the factory would be scoring groups of 17.5" at 500yd (450m) which is pretty much torso-sized or at least torso-and-arms. That’s the WORST possible example that still meets QC. Of course there would not be any minimum to MOA. What, is a Military going to tell an arms manufacturer, “Excuse me, this rifle is simply too accurate, we demand that you set a minimum to how wide the groupings can be.” That’s a rather funny thought.