STG had a rate of fire of between 550 and 600, which is slightly less. Not identical.
Snipers I refer to are designated marksmen, and also actual sniper teams(WW2 soviet infantry platoons typically having a team as messengers/snipers, again I cant find much of anything on 50s and 60s era Soviet infantry ToE). And yes, the M4 is actually less accurate at range than the STG, because the M4 is a carbine with a far shorter barrel, firing a round designed for a far longer barrel while the STG fired a round designed for it to use. The relatively poor performance of the M4 at range is why US military units still keep some M16A4s handy as a support weapon.
A major war in a place where they had to fight up-close and personal in mountainous jungle. Till then most fighting the PLA had to deal with was fairly wide open.
How a government uses something has no bearing on its design, yes. That is, until they go and hold trials for a weapon to meet specific requirements(oh wait) or ask for certain things to be changed(hang on a second).
How to you have a rate of fire "between" anything? There isn't a random factor with it, its just rounding. In any case, the snipers are just what the Soviets call their DMs, though I don't doubt they had actual sniper snipers too it is getting way off topic. I doubt the M4 is less accurate, even at at range. It has half a centurie's worth of ballistics development into it . Seriously, your claims that this gun holds a candle to modern weaponry is probably the most annoying of all. It was a neat gun for historic reasons, but it wasn't a wonder weapon that can shoot a century ahead of its time. A musket with an incredibly long barrel isn't going to be more accurate than a modern weapon due to that fact. The M4 has a range of 500 meters for point targets, 600 for area targets. That is twice what the museum peace has, an effective range of 300 meters. Lets not get into M4 vs M1614 now (and the larger carbine vs full sized), since we have our hands full with this already.
Here are the conflicts China got into between getting these guns and changing to focus on AKs:
Second Taiwan Strait Crisis: (Pretty much an artillery duel. Shelled each other until ROC ran out of bullets. The PRC took the opportunity to use up expired/expiring ammunition while training artillery crews. Not much a chance to use a rifle here.)
1959 Tibetan uprising (Fairly major conflict, against poorly armed and majorly outnumbered guerillas close to home. Surprise! The gun is better then the even more outdated and poorly supplies of their enemies.)
Campaign at the China–Burma border (Jungle warfare against outnumbered Nationalists. Showed that China had a lot of shortcomings militarily, at that you were wrong about China not having a jungle war between here and there. Non-combat casualties were higher than combat casualties on China's side, and most Nationalists escaped. Still not major, around 2k casualties, 800 of which were from the jungle.)
Sino-Indian War (China invades an unsuspecting India, mountain fighting fairly large conflict but the navies and air force spent the war sitting on their hands. 2k killed and a bunch more wounded/captured.)
'Nam. First major conflict since they used the guns, immediately realize they need to use the AKs instead. Hundreds of thousands to possibly over a million dead not counting civilians.
So there you have it. They don't need a decent small arm for general issue when they are beating down a small group of rebels, when they got into an -actual- war they realized how outgunned they were and upgraded to something decent.
They didn't ask anything to be changed for the AK, and while they were asked to meet specific requirements that simply means their quality is better then a gun that was cobbled together by a group of Nazis who where already getting their buts kicked. The soviets didn't exactly have plans for how the assault rifle would effectively be used when they created it, and I am not sure you have any idea how they were used. Even then, this doesn't fix the many problems with the weapon I brought up earlier, or the ones I didn't feel the need to bring up. Many rifles are more accurate then the STG when the soldier has to hold on to the magazine to shoot his gun due to the place he is supposed to put his hands heating up too much to be useful after firing a single magazine. It is a good historical gun, it isn't a good gun to equip our troops with. Just give them the perfectly good AKs and leave the German's gun to the museums.
**EDIT**
Back to the game for a moment, I think everyone voted for the K-1 MBT. For procurement, I like the autogun idea. It should take out whatever they plan to use against our jet in addition to taking out their bombers more effectively. The K-1 should push back the enemy tanks in the meantime, and I doubt they will focus on infantry weapons enough to push our ground forces back so we can at least leave that for later.