- Blue Angle LD

First Impressions
The AMF Blue Angle LD, released around 1985, is a technically specific variation on the popular Blue Angle. The "LD" stands for low density and refers to a modification of the inner weight block. While the outer shell uses the identical grabby blue urethane compound as the standard model, the lighter core changes the mass distribution. Physically, that results in a higher RG (radius of gyration). In other words, the ball is less inclined to enter rotation early than the standard version. Visually it's hard to tell apart from the classic Blue Angle apart from the marking, but on the lane it shows a distinctly delayed response. The surface is dull from the factory to guarantee a baseline of traction, but the engine inside works against burning up too early in the heads.
Comparison
Against the regular AMF Angle Blue (standard density), the LD shows significantly more length. Where the normal Blue Angle often starts reading the lane early and draws a smooth, round arc, the LD seems to skid effortlessly across the first boards. It stores energy longer and releases it further down the lane, which produces a somewhat more defined reaction at the breakpoint while staying controlled in the way urethane always is. Compared to the AMF Gold Angle, the Blue Angle LD offers more total hook and traction, but plays longer than the aggressive AMF Black Angle. It was developed to fill exactly the gap where the black or normal blue Angle starts rolling too early but the gold one doesn't do enough work.
On the Lanes
The AMF Blue Angle LD is an excellent tool for lanes where the heads are already heavily played or dried out. Thanks to the low-density core, it ignores early friction better than almost any other urethane ball in its class. It's ideal for the transition phase, when you notice your standard ball losing energy before it reaches the pocket. If you struggle with too little ball speed, you'll benefit from the built-in delay of the core, which helps get the ball further down the lane. On very long or heavy oil, though, it's less effective, since the core lacks the mass to build traction early enough and mix the pins with real power.