Your Army HSc was produced in January 1944 which places it squarely within Jan Still's 4th Variation category defined as Eagle/135 Acceptance mark with Military Blue or Phosphate finish. Military Blue finish became the standard during Mauser's Transitional period from August to November of 1942. If you would like to review the Still Variations see the "HSc Production Chart" sticky at the top of this section.
Hope that helps. Anything else, let me know.