Hi niko, something like Rail revolve can be better for the rounded tip shape.

Or also the "maintain tangent" option for sweep can do a good job of this because it keeps the profiles as slices of parallel planes as they move forward.

The pinching happens when things slide along different length rails, creating some rotation/wobbling type effect. You can maybe see that if you turn on control points for the surfaces.


In order to use "maintain tangent" your profiles have to start out as parallel planes though, currently your front profile does not seem to be planar.


Check out this previous post for a similar example to what you want, using "maintain tangent" on 2-rail sweep:
http://moi3d.com/forum/index.php?webtag=MOI&msg=2908.13


Or sometimes it can be good to do just the tip as a separate surface using revolve or rail revolve and then blend that to the main part.

- Michael