One of the guys that used to bowl in a late night shift with my Dad in a Masonic league had lost his left hand and part of his right hand in an accident at work.He only had 4 fingers on his right hand.One of the touring pros from that era----no,I don't remember his name----heard about it because this guy and the pro were both veterans.Anyway,he came to the bowlign alley one weekend with the tour truck and drilled this guy two balls for free.
 Both balls had four holes.I don't remember the drillings.They were a Yellow Dot and an AMF Three Dot Classic.The gave him a weekends worth of lessons.The guy in the league averaged in the 190s as I remember.
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Chris
 JTTDB---Just Throw The Damn Ball
 Don't "think"---that ball isn't in your bag yet..........

I have a pinky finger in all of my equipment. I feel it makes the ball steadier on my hand, and it helps me project the ball down the lane. I have never noticed a grabbing problem from having it.

It keeps the lateral strain on my wrist to a minimum and allows me to distribute weight more evenly across my hand. I've tried going back to a standard grip only to return soon afterward to using the pinky finger.

I have never tried an index finger hole.

Jess