I initially had quite a bit of trouble extruding the nylon. It would ramen like crazy. I blended it with some carbon black to achieve my desired material properties, and passed it through the extruder a couple of times. After a while it extruded well.
So there are two potential reasons why I started making good filament instead of ramen:
1. Passing the nylon through twice dried it out.
2. The carbon black decreased the melt flow index, or something, and that caused the nylon to extrude more successfully.
I am leaning towards reason #1 as being the critical element. Dry your nylon!
In more recent batches I am drying it out in a glass pyrex pan in the oven at 100 degrees C.