Primers falling out

[Dr.Phil]

..curious, what ratio of sealant to acetone do you use?

I thin it by eye.
Add a small bit of acetone, mix well, then see if it is thin enough to be drawn into a needle.
I was always having to add acetone anyway, because it would thicken when not used for awhile.
(The same results can be had using nail polish.)
It doesn't take much to seal and retain the primer.

I would prefer not to take the time to do the sealing, but after getting bit a few times with a stray primer locking up the gun, I feel it is worth it.
viewtopic.php?t=97730

Using a go / no go gauge is great, but that adds time.
I prefer to use an RCBS hand primer so that I can feel each one and reject it immediately if it is too loose.
If you are using a progressive press that has a priming system and are using the gauge, you are using the same amount of time and effort.

[AR-300]

I deprime them and then gauge them. That way loose brass doesn't go further in the resize, trim case prep process. Reject them early long before priming.