Note: This page is taken from n.wikia.com.
(As written in the N in-game help)
These drones are equipped with a rapid-fire (but not so accurate) machinegun.The chaingun drone, which is similar to the laser drone, moves rather slowly but can actually be quite deadly. Once the ninja enters its sight range, it will stop, charge up, and fire a stream of bullets at him. They kill upon contact like everything else. The chaingun drone itself, however, does not kill the player upon contact, unlike the zap drone. The difference between this drone and the laser drone is that since the bullets aren't continuous, it is possible to jump through the line of fire and survive (which requires some luck). However, the chaingun drone doesn't shoot at a single spot - rather it can sweep its fire, making it hell to dodge it in enclosed areas. Highscorers somehow manage to do this often in levels such as Nv1.4's 91-4: blastphemy.
To avoid chaingun drones, a good method is to try to set it off, and use its charge-up time to move away, or wait till it has finished a salvo and is reloading (which takes some time) to move out of range. If one cannot simply stay out of range, and must dodge bullets, they should move just before the drone is going go to fire. The player can then jump. The time the ninja can stay in the air is roughly equal to that of the barrage fired by the chaingun drone. Note that the drone does aim constantly at the ninja before it fires (meaning that as the player moves, the drone will rotate to still aim at them), but while it fires, it does not aim at the ninja; inestead it proceeds with a sweep that covers a wider or lesser area depending on how fast the drone was last turning. It is possible to get inbetween bullets while it's shooting and still survive.