Depends what ammo they use. With hand loaded match grade ammo, it will do just fine. With cheap, mass produced HMG ammo you might need a little luck to hit a man sized target that far out, but that can be mitigated somewhat by the semi-auto nature of the rifle, so if you are shooting at a person at 1km+ ranges with cheap ammo, you would be trained, or learn to fire off a quick two or three round group to maximise your hit probability.
But realistically, if you are shooting at targets on the battlefield over a km away, you would want to be shooting at a cluster of targets instead of an individual most of the time. The longest sniper kill on record, for example, was made against a member of a Taliban mortor team. Whether the shot hit the guy the sniper was actually aiming for only the sniper himself can say. It was also never publicly disclosed if it was a one-shot-kill, or if the sniper in question just squeezed off a mag and just got lucky.
That Taliban kill was by a Canadian solider who used 50 cal round from a McMillan, it was on a ridge and it took 4 shots, the final shot was aimed so far off the target that the sniper himself couldnt believe it when he struck, it was recorded at a astounding 2.5km
A sniper from a special forces commando unit are trained easily to hit at 1,000m, less than that is normal, I mean 700-800 metres is no sweat for a well trained sniper with a good gun
But the sniper is just part of the story, the spotter must be of a similar calibre and weather conditions like wind speed, altitude, visability and pressure also play a big role
In return some Taliban fighters have used Dragunov sniper rifles to hit coalition soldiers from 1,000m away, on one occasion one 7.62mm round came through a RAF Chinnok windscreen and hit the pilot in the head who then flew his helicopter all the way back home bleeding from his head, he survived due to his bulletproof helmet which was partially penetrated
Sniper schools have really upped thier tempo after the wars in Afghanistan and Iraq and here has been some remarkable shots