I don't think this is a great idea, if only you have a 6-7 ball arsenal. I do think it is an ok idea if you have a huge arsenal, and bowl for a living. With 6-7 balls, you want to be able to cover as many pattern variations as possible. What you will find, is sometimes a weight block or cover will just not work in a certain bowling center, or on a certain lane condition. Now, if you were to add a Virtual Energy, at least now you are adding a different cover with that core you like so much.
An "arsenal" of bowling balls is to give you different options to score no matter what is on the lanes. You want to be able to cover as many variables as possible with as few balls as possible, and do the rest with release and technique.
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Tommy Gollick
Storm Regional/Pro Shop staff
Red Crown Pro Shop Harrisburg, PA
stormbowling.com