Nordenfelt was pushing hard, as he could see the Gardner gaining popularity among land forces.  He seemed to have the Navy wrapped up, they were pretty happy with 5 barrel mounts on their ships. But on land, Brits favored the Gardner, however, Nordenfelt stressed the fact that his 2 and 3 barrel guns weighed less than the one barrel Gardner.  (Of course, aren't more barrels always better?)  And the 3 barrel gun broke down to only 35 parts, where the Gardner had that many with only one barrel. (Again with the one barrel argument!)

Nordenfelt multibarreled guns

The Nordenfelts were also galvanized, which should have kept them from rusting, especially since the British Army always seemed to be involved in the worst parts of the world, weather wise... It has been said that only 3 horses were needed to carry everything for a 3 barrel gun, including a certain amount of ammunition.  But wagons were needed to carry a lot of ammunition if you were really going to get serious.  But if you really wanted to be ready to go, fully assembled and loaded Nordenfelts could be carried by wagons, dragged off at the point of combat and put in action in minutes.  

Nordenfelt limber

Nordenfelts claim that 2, 3 or even 4 barrels were much better was lost when he developed the single barrel Nordenfelt machine gun, at 13 pounds and meant to be carried by horse soldiers, although not to be used on horseback.  Not much heavier than the troopers rifle, it supposedly could shoot 180 rounds per minute.
The Nordenfelts best qualities were simplicity, and being made from steel.  The multiple barreled guns were light and could be taken down and reassembled in minutes with no tools, try that with a Gatling. 

Nordenfelt gun