Yep, that calculator on bowlspot.com is certainly helpful. I used it as a point of departure, a place of reference so I could figure out for myself where I needed to stand at the start of the approach and where I needed to target.
I wrote a handful of combinations down for the 10, the 7, the 6, and the 4, targeting the 15 and the 20.
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Hammer Razyr 15#
Storm Virtual Energy 15#
T-Zone 15#
Skill level: learning, working on it!