Abstracts of muster rolls of NYS Volunteer Units that served during the Civil War (Series 13775) are available on self-service microfilm at the New York State Archives. The Archives does NOT have original muster rolls.
Content varies, but abstracts generally provide: enlistment date; age; place of enlistment and for how long; date mustered in; grade; company; regiment; date left organization; reason for leaving (killed, discharged, deserted, etc.); in what grade; and "remarks."