having optics dramatically increase the engagement range, thus is very important. Glad PLA is catching on.
Well range is iffy.
Back from the Chinese hand cannon the chances of actually hitting anything were pretty low. This carried over with every gun forerunner and eventually the musket. In theory historic black powder muskets actually have a longer range then a Modern assault rifle. But the chances of actually hitting anything are not so great this is why you had ranked fire with each tank firing you had a better chance of not per say killing but wounding and intimidating the enemy into breaking ranks at which point you fix Bayonets and run down a disorganized mob bayonetting those that resist ensuring they can't fight, chasing off some and capturing others ending their threat. The rifled barrel gave accuracy changing the situation in the U.S. the Kentucky rifle was flimsy compared to the British military rifle but it was far more accurate and ranging this also played out in the British Afghan conflict, the Afghans built homemade rifles and were firing from mountain tops into British ranks from very long ranges.
Then came the mini ball and smokeless powder.
These advents increased range more now with a good shooter at most range you could hit a mansized target no problem and in theory beyond that giving rise to the theory to volley fire. Add in self contained bullets and some armies felt you could range out to almost a mile with using the rifle like a tiny artillery peice. They would aim using volley sights and fire at very high bore axis.
Of course theory and practice didn't work that way. As volleys were in accurate and reloading and aiming took time in which the enemy could close in.
Self contained bullets also rise to rapid firing repeaters. And where after each volley you had to reaim a repeater could just be cycled and fired again. Especially smaller calibre weapons which were easier to cycle and reaim this ended volley fire and brought ranges back down. Add in the advent of early rapid firing weapons like the gatling gun and it became more and more realistic that anything beyond 800 meters is more a specialist type. Entrenchment made this even more and more realistic that even 700 meters was dreaming as armies built up close quarters engagement and turned long range into the realms of No man's land by mines, Barbed wire, trenches and traditional parapits. This gave birth to hand grenades and pistol calibre sub machine guns close quarters weapons well the mortar, tank, rocket and howitzer became the long range.
The assault rifle came about as an improved version of the concept of the SMG. Where the SMG sacrificed range and accuracy for rate of fire to clear a trench but not operate beyond 50 meters. The assault rifle made the better bargain by still able to fire out to 400-500meters and be accurate and light well having rapid fire.
The optical gunsight came about more to do with 1) low light.
In low light iron sights being blunt suck. The Human eye trades off a lot of what it needs for iron sights to operate In The dark.
2) acquisition.
Red dots came about for competition guns before military rifles. But before that they were for target acquisition by anti aircraft and aircraft guns.
3) Magnified optics on rifles don't give range as much as the ability to use that range. ACOG isn't much more powerful then the sights used on world war era sniper and marksman rifles. These were just modified Service rifles. What it gives is faster acquisition and better view of the target. It's not ranging beyond what you can see it's zooming.