That's what I thought at first but if you watch more carefully, there's a brief momentary hanging of case on top that causes the swing of the rim to knock the bottom case mouth to tipping it over.
Think about it.
If there's nothing that's "hanging up" the dropping of cases, then next case should simply be resting on case mouth of bottom case.
If we rule that out, then what could be happening is bottom case "bouncing off" the slide surface and colliding with the bottom of top case and tipping over from the collision, which may indeed be what could be happening.
BUT my point in conducting "root cause analysis" is not assuming anything but VERIFYING everything so we can start "ruling out" one thing after another to end up with true "root cause" of why the cases are tipping over.
That's my point I am trying to make ... To conduct the "root cause analysis" without prejudice of assumption.
ONLY when we TRULY have identified the CAUSE, can we work on RESOLUTION of the PROBLEM.
(And believe me, I have learned this from my various myth busting threads ... assumptions, subjective opinions and even educated "WAG" don't apply when "myth busting" and/or conducting "root cause analysis" to get to the true cause of the problem.
I am simply sharing with you the proper approach to addressing reloading issues so you can always correctly and accurately identify the true cause to fix it permanently ... That's what we have done for the pre-2018 Pro 1000 thread and this SPP/Pro 6000 thread.
Were we wrong on some of our resolution approach?
Sure.
But for over four years, THR as a group kept focusing on the true underlying cause and eventually, we addressed all the issues to resolution. And I believe that's the hallmark of "High Road" approach to reloading.
And I did similar in "real world" approach to accurizing factory 10/22 to produce 1/2" groups at 50 yards using CCI SV (3/4" with Aguila 40 gr LRN/CPRN).