The problem with urethane is that you need a lot of ball speed to get them to work on a house shot because they typically have a lot of surface that chews up the front part of the lanes (the heads). As plastic spare balls have a simple pancake weight block, I'm wondering how you had it drilled "a little strong." If you don't have a lot of ball speed, you are probably better off looking at an entry level reactive ball. Being speed challenged (old) myself, I often use a Brunswick Twist which has a very high rg and a very low differential. It is also drilled with a 6" pin-to-PAP to weaken it further.
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