- Black Ninja

First Impressions
The AMF Black Ninja, which took the bowling world by storm around 1991/1992, marks one of the most important technological turning points in AMF's history. Visually it comes in a purist, menacing black, broken up only by the iconic golden Ninja logo. Technically, this ball was AMF's answer to the beginning of the reactive revolution. Inside sits the groundbreaking Ninja core (often referred to as the Shredder or high-density block), which differed fundamentally from the pancake cores common at the time. This core produces a differential that was high for its era, allowing the ball to generate significant track flare. The coverstock is a highly developed urethane blend that already contained the first additives from reactive chemistry, in order to create more friction on the heavily oiled wood lanes of the day than conventional urethane could.
Comparison
Compared directly to its spiritual predecessor, the AMF Black Cobra, the Black Ninja plays in a completely different league in terms of dynamics. Where the Cobra still relied heavily on its surface and ran a calm arc, the Ninja generates considerably more drive and angle on the backend thanks to its core. Set against the NuLine X-Calibur (the pioneer of reactive balls in that era), the Black Ninja was considered somewhat more controllable and less jumpy. The X-Calibur often had a more extreme skid/flip motion, while the Ninja offered a heavier, more powerful roll to the pocket. Against the later AMF Sumo, the Ninja looked longer and more angular; the Sumo was better known for early roll and pushing massive amounts of oil.
On the Lanes
In its heyday in the early '90s, the AMF Black Ninja was a high-performance ball for heavy oil. From today's perspective its range of use has shifted: it's an excellent tool for medium to dry conditions or short sport patterns. Its strength lies in combining the forgiveness of urethane with the dynamics of a real core. It's ideal if you have to play dry lanes (late shift) but find that a pure plastic ball doesn't do enough work while modern reactive balls jump too aggressively. The Ninja reads the lane reliably, doesn't punish over-rotation immediately with a gutter ball, and still provides enough energy transfer (carry) to mix the pins even on light hits.