The prior responses are not entirely accurate... There are 100 times as many gunsmiths that specialize in slicking up $1200+ 1911's like Kimbers and such. That doesn't say anything about those guns quality. What it says is that there are people willing to pay to get better performance from that kind of gun and taking those guns to a higher level of performance. It is the same with R92's. A ton of people people buy them to use for Cowboy Action shooting because for $450 for the gun + $200 (including shipping) for a full action job the price is still better than almost any other Cowboy Action Lever Rifle that is already at competition level when brand new.
The R92 is an inexpensive lever action rifle, but it is not a cheap rifle by any means. Being inexpensive the fit and finish is not as good as a more expensive gun will have off the shelf. As such it can take some time and effort to get the action to where you want it. However, by all reports it will get pretty darn smooth with enough shooting and/or cycles of the lever.
I have a new R92 in .45LC and the action was reasonably smooth out of the box and has gotten a bit smoother after just my first session shooting it. It is already just as good as my Marlin 1895 Guide Gun's action was when it was brand new and is only looking to get better. So you SHOULD be getting pretty decent action out of the box, which it sounds like you are not.
So given all that, I would hazard a guess that the main problem is that the gun was sitting unused for a few years. That can gum up the works a little in a firearm as complex as a lever action. I would suggest you oil it up, hold the trigger down, and cycle the lever until it is gets smoother. If 3 or 4 hundred cycles doesn't help then I would suggest you go to http://store.stevesgunz.com/
and order his kit with the DVD on how to fully disassemble the R92 as well as a new follower and spring. However, if you have the metal mag follower already then just get the DVD and spring separately. But this hopefully won't be needed at all.