Often you need to create special finishes for coil springs. After you have made a spring using the Helix feature and Sweep, you can easily create a partial revolve at each end of the coil.
Select the face of the coil end and select Revolve Boss.
In Sketch Mode, select Convert Entities.
Create a Centerline at the desired location. Mine was made along the origin and vertical.
Select the desired Revolve angle.
In the last two images, the coil is shown before and after the creation of the revolve feature.