Ruger did for a time have min-14's in 1:7 twist...no longer. But they made enough of them, that they're "findable".
The serial numbers are approximately:
run start: 1989: 185-56000 or for the Ranch Rifle: 187-84000
run finish: 1994: 186-35000 or for the Ranch Rifle: 188-75000
Most of the major AR makers offer one or more.
ar-15
A 1IN7 gradient refers to a slope where for every 7 units horizontally, the elevation increases or decreases by 1 unit vertically. This means that the slope is steep, with a relatively quick change in elevation over a short horizontal distance.