Again, doesn't matter how 'Fast' you go when it's over indexing, moving shell plate too far and it snaps back to the detent...
Just a mechanical fact.
You will also have increased 'Snap' issues when the shell plate stops short, not enough rotation,
And the detent ball/spring has to 'Snap' the shell plate into position.
Not as common, but it does happen.
ADJUST YOUR PRESS!
If you haven't read the failure chart & fixes,
And you don't know how to adjust the smallest things on your press,
You aren't going to like the press very much...
It's a COMPLICATED piece of machinery, but Dillon 'Idiot Proofs' as much as they can, THE MACHINE STILL NEEDS TO BE ADJUSTED!
Look at Mr. Morris's photo, right under the shell plate is the ram head.
Right under the head, there is a 'Black' block on the side of the frame.
That block with angled top adjusts the rotation stop of the shell plate...
Two screws to adjust, stop rotation EXACTLY where it's supposed to stop.
They come 'Ready To Run', but not PRECISELY adjusted.
If that doesn't stop/reduce the issue to acceptable levels,
Then order the low pressure spring/low mass ball kit.
Cheap & effective when you are loading really full cases.
Dillon makes a VERY high quality product,
They can not possably adjust YOUR press for every round YOU might come up with...
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Ain't it just like the LNL guys to go off the deep end everytime some minor issue comes up about Dillon presses?
I think they have a HUGE issue with 'Ram Envy'!