Mr. Bulk,
FWIW my A19 that didn't fit flush in the above thread was quite a few years old according to the seller.
The one that does fit flush still has a hairs width of light visible through where it meets the P body, like some Arc LS bezels. When screwed down it is also smooth and level with the body on one side yet ever so slightly off on the other. This will only bother you if you are prone to washing your hands more than twenty times a day.
I bought both of mine used at fair prices. The obvious answer is to try before you buy if possible...
Jim