Weight hole below the VAL?  Or do you mean below the grip center line?

As for #2, a large shallow hole is only removing weight to make the ball legal.  A smaller deep (3"+) will remove core material altering the core dynamics depending on the location.

Check out BrunsNick's demo on weight hole placement!
http://www.brunsnick.com/bowling_ball_x_hole_video.html
and here:
http://www.brunsnick.com/xhole2.html
If the video doesn't play scroll down toward the bottom and click on the demo!
Great demo by BrunsNick/Nick Smith

Isnt a p4 hole going to be inside the val and typically close to the thumb hole to begin with?

Well, the location of any of the gradient balance holes are determined by the location of the PSA.  My REAX has the PSA pretty much right on my VAL which would place the balance hole on my VAL regardless of it being P1, P2, P3, or P4.  My Defiant Soul has the PSA just to the right of my thumb.  For that ball P1 would be on the VAL about 2.25" above my PAP, P2 would be close to my PAP, P3 would be about the midpoint of a line from my PAP to the PSA.  P4 would not be an option with the PSA so close to my thumb.

Was this psa location prior to drilling or after drilling?

Well, no determinator so prior.

The biggest factors will be hole size and depth and how far inside or outside you move it.


As mentioned with the Brunsnick vid it gives you placements both inside and outside of the VAL along with a great visual of the effects.

Going off your post I guess we are to use the example of an asymmetric ball, with the PSA on your VAL and your wanting to add a p4 x-hole either just inside or just outside of the VAL.

In that example just inside or outside by 1" would have almost the exact same effect as being on the MARKED psa of the bowling ball. Using the gradient line systems off of the pre-drilled locations, which is assumed by many, will get you very close to the same results as if you had a determinator and spun the ball after drilling.

This is probably how a large % of balls are done due to the lack of availability most have to a determinator or similar product.

In the real world if the PSA is on the VAL prior to drilling after drilling it will shift inside closer to the thumb. Maybe 1/8" or a 1/4" max. So by drilling inside of your marked PSA by an 1" for example your still very close to the new actual PSA location. Depending on how far inside you drill the hole along with the size will shift the PSA even more which also changes the drill angle of your bowling ball.


Where the effect would be different is on say a p1 or p2, where being inside could reduce the reaction of the ball more then being spot on. Enough to be noticeable? Hard to say with out having a specific example to try out. Such as the actual hole size and actual distance inside of the p1 p2 p3 pr p4 location.

 With the blueprint software you could get a more accurate idea.

Also don't get hung up on the VAL for every ball. On an asymmetric if the psa is on the VAL then it is relative if the psa is closer to the thumb then the actual correct locations for the p3 and p4 locations will be inside of the VAL.

You can see that on page 2 of the link.

 http://wiki.bowlingchat.net/wiki/images/c/c6/GradientLine.pdf