Is there a way to find out exactly how many people of a certain MOS are in the Army?

You can look at the force authorizations under FMSWEB or the actual number in EDAS, but none of that will be published because that would be sensitive information

HRC or DA might know but that is not something that would be published as open source. The numbers would fluctuate too much with those retiring, those being put out, those graduating from AIT and those reclassing.

Go to the army web site