I'd say an 8pin is the only true tap.  But at the same time, I've seen people who's back end reaction caused a lot of 8pins.  My resolution when that happens, I move up 2-3 inches, and believe it or not it makes a huge difference in my pocket action.  It doesn't hit light, just produces a different bounce for the pin (the 5 I think) that gets a bad tap out to leave the 8.

At least it works for me!

Assuming all the pins are on spot, the 8 pin (righthander) is the only one there is no adjustment for. Just plain bad luck. This link on this website shows the best slo-mo video I've seen about Stone 8s. I've have rechecked all the stone 8s from PBA classic shows I've recorded back into the 70s and same thing...the headpin hits the 5. All these years, coaches (including me) have taught that the ball chops the 5 off the 8. Now, we know.
http://www.teamstatpro.com/solid8pin.htm
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www.buildanarsenal.com

I agree with the 8.  9-pins are almost always too much angle, too high, or too much drive.  The ball exits through the 8-pin spot by going 1-3-5-8 instead of 1-3-5-9.  It's simple to adjust for that situation.  10s are usually either weak or ringing and we know how to adjust for them.  You just can't adjust for 8s.  It's not a bad shot, and 9 other times, you'd've carried it fine.  Ask Randy Pedersen.

SH

Edited on 10/17/2006 3:48 PM

I'd be more convinced of the head pin hitting the 5 pin first if it were an overhead view. There is quite a distance between the 1 and 5. I see the ball pushing the headpin out of the way and then hitting the 5

Guys,

  The solid eight-pin tap IS caused by the headpin hitting the five-pin, but there is a process to it. You may not belive me, but I have worn out three V.C.R.'s (remember those things?) playing and re-playing the p.b.a. telecasts. Here is what happens.

  The ball enters the pocket very flush on the headpin, almost high, but not quite, and due to the entry angle, it contacts the headpin at the perfect spot to get the reaction it takes.

  The headpin is slammed into the 2 pin so hard and so quickly, that it rebounds off the 2 pin, butt first, back into the path of the oncoming ball and is "trapped" behind the ball for just a split second ina prone position.

  The ball then contacts the headpin again, this time while it is "trapped" behind the ball. This causes the HEADPIN to hit the five pin a fraction of a second and at a fraction of an inch different trajectory than the ball would have, causing the 5 pin to go straight, directly back, missing the 8 pin altogether. The headpin then rolls out from behind the ball, just barely missing the 8 pin itsself. The headpin goes into the side gutter, the ball drives through the rack hitting the 1-3-5 and9pins like it is supposed to on a perfect delivery.

  All other pin action is the same. The headpin causes the five pin to go straight back, missing the eight pin and there is nothing else left to hit it unless you over throw the ball and it over hooks enough for you to get lucky and hit it with the ball.

  Argue all you may.  Get a tape machine and watch. You will see it, no matter how many times and how many different eight pin leaves you look at, they are ALWAYS the same if it truley was a tap.
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"The difference between stupidity and genius is that genius has its limits."
Albert Einstein

I had that problem before but fixed that on my throw. If I start living 8 or 7 pin. All I do is moved 1 board right then 1 inch back. Took me a while to figured out but works for me on any ball I used. If I just moved right then it leave to 10 pin.

I always thought thE true tap was a flush 7-9 (for righties) because A. you pounded the hole flush and B. your reward is an open!!!