This is my first time printing on a newly built printer, so I'm wondering what I did wrong. .40mm e3dv6 nozzle heated to 250degC, starting extruding 3mm ABS at 15mm/s. Within 30 seconds the filament stopped feeding, and when I retracted it the nozzle was jammed.

Disassembled, confirmed the heat break was free and clear, with the plastic stuck solid in the nozzle. What could I have done to cause this "hollow" jam?

download_20151122_170602.jpg

I'm currently switching over to the magma hotend while this soaks in acetone.