Richard -
You're on the right track, but in my experience it's unusual to find quartermaster records or company commander's records that reference arms or ammuntion. Ordinarily the job of the QM strictly included clothing, shoes, belts, tents, wagons, mules, paper forms -- anything but arms, ammunition and related items. I have been through files on microfilm for every officer in a regiment with barely a mention of arms. If you come across records of a captain or lieutenant who served as an ordnance officer, then you're much more likely to find these kind of records.