Here is a Hamilton navigational watch model#4992B but it has a 3C2552. marking instead of the typical 4C0000. Does anyone have an answer to this question i have on this piece...

Here is a photo of the front side of my 4992B/3C2552 Hamilton navigational watch...

And here is photo of the movement in question, Hamilton navigational watch, 4992b./3c2552.

Maybe someone has and answer to this perplexing question of why mismatched grade markings...

I am not an expert in these so I do not know the answer, though there is always the possibility in any watch that over the years there has been work done by watchmakers and damaged parts can be replaced. Back when these were in use there were watchmakers in the Army whose job it was to keep these in top running condition and they had no idea that collectors would one day care. This may not be the case in this watch and hopefully someone will know, but the replacement issue, or even a watch partially or entirely made up from parts is always a possibility in any old watch.

Hi,
ACCORDING TO Marvin Whitney , The production of
3992B was 2494 for Canadian Gov. your ser.no.is 58,higher I have one 136 higher than production I don't have any proof , but would think rather than discard 3C plates,they would have use them on 4992B,which is the same movement , or with a over run of 3992B put on 4992B bridge. Hopefully It was done by Hamilton. Any comment will be appreciated.
Hub.

I believe that is spot on. Like you said used spill over of 3C plates... thank you for your input Hubert,