Dear Mr. Bull,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located the Compiled Service Records of Soldiers Who Served in the American Army During the Revolutionary War in the War Department Collection of Revolutionary War Records (Record Group 93) however we could not located a service record for either Ambrose or Micajah Bul. These records have been digitized and are available using the Catalog.
These records were not created during the Revolutionary War, but were created by the Department of War starting in the 1890s from extant records among its files in an attempt to create substitutes for records destroyed by fires in 1800 and 1814. Because the Department was not able to reconstruct every record, a soldier may have fought in a Continental Army unit during the war, but there may not be a compiled military service record for him. Furthermore, many soldiers that served in state militias rather than in the Continental Army are not included in these records.
We hope this is helpful. Best of luck with your family research!
Thank you for these valuable links. I appreciate your help.