NLB has much less Flinch than the rest of the sniper rifles. Which is good because you sacrifice a Primary weapon (which is apparently essential now) and have to rely on popping skulls to get anywhere. This is also the problem as well because you can hose down an NLB user and they can smoothly take your head off. My suggestion? Don't challenge them unless you have a sniper or a scout rifle. If they're in close range you can win but outside of that you may not stand a chance.

Challanging a sniper when they have an obvious advantage is always a bad idea, i suggest using a Low RoF pulse like pantheon shot it can 2 burst max armor gaurdians (if youre landing head shots) and staggers enough to make things more difficult for the onr being challanged.