Quoted:
I'm sorry to say both Scalce's and hondaciv's posts above are both wrong because the Indexer Block has nothing to do with the primer adjustment. It's solely for advancing the shellplate, not moving the Platform below it. My recommended adjustment then is solely for controlling how far the Indexing Ring, and therefore the Indexing Pawl, will advance. This is the only method available to adjust the Shellplate advance.
We never said it adjusts anything on the platform or the priming assembly.
Think about what holds your case that needs to be primed.
Could it be the shellplate?
If the shellplate indexes too far clockwise or counter-clockwise, your case which needs to be primed in station 2, may be out of alignment and therfore your primer(which is static) will not be centered in the case.
Primer alignment isn't always an issue depending on the caliber, brass, and primer but if you have some tight primer pockets with primers that typically measure on the high end, you will have issues.
This is why some people complain that LC 556 brass is difficult to prime on a 650 with CCI primers.
You can tell your priming station may be out of alignment if you see the shellplate get forced slightly clockwise or counterclockwise while priming, and then settle back in place when you bring the handle to rest.
Adjusting the indexer block is part of the troubleshooting guide if you have hard or incomplete indeing.
Take a look at page 41 of the online 650 manual from 2007:
RTFM
Hard or Incomplete Indexing
A. Shellplate not indexing smoothly.
9. Ring indexer (#13677) worn or indexer
block (#16776) needs adjusted.
So while this may have helped your 650 with some powder spillage, it's not a new idea and could totally misalign someone else's priming.
We just wanted people to be aware that it may help lessen one issue but cause another.