Cjackson, Ive been drilling balls for no thumb bowlers for over 20 years just because you dont use your thumb doesnt mean you still cant drill the thumb hole as your balance hole. I throw the ball between 17.5-18mph PAP is 4 1/2 over 3/4 down I find what works best for me is lower daul angle drills like 25X4.5X 30 because of my ball speed and rev rate being fo high on both . IF you have any questions or would like some help laying out your next ball just shoot me a PM Id like to help if possible.. good luck
you are allowed to have slugs and tape in a weight hole under USBC rules Just a fyi
USBCs rules on gripping holes read carefully
6. Holes
a. Holes or indentations for gripping purposes shall not exceed five and shall be limited to
one for each finger and one for the thumb, all for the same hand. The player is not required
to use all finger holes in any specific delivery, but they must be able to demonstrate, with
the same hand, that each gripping hole can be simultaneously used for gripping purposes.
Any thumb hole that is not used for gripping purposes during the delivery would be
classified as a balance hole.
b. One hole for balance purposes, not to exceed 1¼ inch in diameter is permitted. (Slugs and
bowling tape will be allowed in balance holes, however interchangeable devices are not
allowed).
1) Any hole that cannot be reasonably shown to be used with a single hand is
classified as a balance hole.
2) Balance holes may not intersect gripping holes
c. One vent hole for each finger and/or thumb hole, not to exceed ¼ inch in diameter is
permitted.
d. One mill hole for inspection purposes not to exceed 5⁄8 inch in diameter and 1⁄8 inch in
depth is permitted.