Lets here you experiences with the failure of these pistons, And your theory's about why they brake the top ring land?  Recent sbc that I built had 3 piston's fail after only one race. I have build many engines using these pistons with no issues and I know about the increased top ring gap factor of .007 x bore which = .028. and the total timing of 34 deg. With all that being said I always run even more top ring gap .035 and they still broke. We have a comp ratio of 10.5 to 1 and use 94 octane fuel and water temp was 215 0r less. Timing marks were checked before the heads were installed.
 Now my theory: The total advance is set at 34deg but it has dam near that at idle about 24* to 26*  which I feel is to much when hot idling causing detonation at this low rpm. Thoughts?      

Not vortic heads.you think that makes a difference?

Update: We put 3 new pistons in the sbc and didn't change anything except the initial timing. Now at idle 1000rpm's it is about 10 deg and 34 total at 3200. We ran 163 laps at OSS without any engine issues. So im thinking all the initial timing we had before (24-28deg @ 1000rpm because of the very lite dist springs was the cause.