I would suggest taking a look at M. L Brown's Firearms in Colonial America . Its secondary source references are not always good, but it does also make use of a lot of primary material. Although it is dealing with foreign armies and hunters, of course, there's a good bit there on Committees of Safety and militias. But these units often would be created rather quickly and also could disappear when they had little use ( the Armory in Williamsburg seem to have suffered from periodic neglect throughout the colonial period) so although this is not something I have deeply dug into, do not be surprised if records of specific units are incomplete. Some of the staff at Old Sturbridge Village have re-enacted a militia unit for a number of years, and there's an exhibit there now: but the last time I checked they had not been able to find an actual period portrait of such a unit and so have been doing a lot of educated guessing about uniforms, etc