It would be a secondary lever action rifle, much like the original Henry Repeater. It would feel much like the sniper rifles now with less range (say 60% of sniper range) and less accuracy. No scopes, only barrel changes.
The accuracy would be what makes it somewhat difficult to use. Much like pistols pre 2.0.
Precision hits increase accuracy and range.
10 in the mag.
That's all I can think of right now while at work. Comment if any of you have any more ideas for it. Need a name and some stats. I'm sure some of you can think of something good.