The JS-2 is a 4 kg (8.8 pound) bolt action rifle with a flash suppressor and five round magazine and scope. This is apparently meant as a true, albeit short range, sniper rifle. An earlier (1989) Type 88 5.8mm sniper rifle was semi-automatic and not really for snipers but rather for the "designated marksman" in each squad.
Noting the success of large scale use of snipers by American forces in Iraq and Afghanistan, China is increasing marksmanship and sniper training for its troops. The Chinese analysts apparently also noted that most sniper kills were at relatively short range (even in Afghanistan). Thus there was some justification for a lighter 5.8mm sniper rifle. The Chinese police are also using the JS-2, but police snipers typically operate at shorter ranges than their military counterparts. Time will tell if this analysis justifying 5.8mm sniper rifles is correct.
Over the last two decades the lowly .22 caliber LR (long rifle) round has become a favorite among snipers. Professional assassins (usually thugs working for organized crime) have long favored using .22 caliber (5.56mm) pistols for their work. While not a powerful round, if you shoot someone up close with a .22 caliber pistol several things should be noted.
1- The victim is dead if you shoot him in the head, which is what pros usually aim for (as these guys like to say, "two in the head and you know he's dead.")
2- There is hardly any sound if you use a silencer and not much even if you don't.
3-A 22 caliber pistol is small, even with a silencer. That makes it easier to conceal and easier to dispose of.
Then in the 1990s the Russians noted that Chechen snipers were effectively using .22 LR (long rifle, them little bullets kids use to hunt squirrels and rabbits with) weapons. Inside towns and cities, the .22 LR sniper was very effective, especially since the Chechens would improvise a very workable silencer by putting a plastic bottle on the end of the rifle's barrel, with a hole in the bottom of the barrel for the bullet to exit. Using a cheap scope, Chechen snipers were very deadly at ranges of less than a hundred meters. Such ranges were pretty common in built up areas. And since you usually did not hear the shot (to the head or face, of course), you had a hard time finding the shooter.
Having suffered from these low tech .22 caliber Chechen snipers for ten years, the Russians have come out with their own professional .22 LR sniper rifle, the SV-99. This is a little heavier (at 3.8 kg/8.3 pounds) than your usual .22 LR rifle but is built for professionals. It has a heavier barrel, a bipod, silencer, and scope. It's a meter (39 inches) long and can accept five, eight, or ten round magazines. There is a compartment in the butt stock for two five round magazines. With the SV-99, at a hundred meters, a skilled shooter can consistently put all rounds in a 12mm (half inch) circle. This is a specialist weapon, most likely used by commandos. But any trained sniper can quickly adapt to using it. And snipers like not being heard. But while the .22 LR is quiet (because it is slower) the military .22 (5.56mm) round is louder. So the Chinese 5.8mm would be difficult to silence well. But if the JS-2 users were supplied with a low power 5.8mm round, and a silencer, well, that would be a different matter entirely.