If you need WW2 information, here are some!

Army Ranks:
  
  E-7 - Private (PVT)
  E-6 - Private First Class (PFC)
  E-5 - Technician 5th Grade (T/5)
  E-5 - Corporal (CPL)
  E-4 - Technician 4th Grade (T/4)
  E-4 - Sergeant (SGT)
  E-3 - Technician 3rd Grade (T/3)
  E-3 - Staff Sergeant (S/SGT)
  E-2 - Technical Sergeant (T/SGT)
  E-1 - Master Sergeant (M/SGT)
  E-1 - First Sergeant (F/SGT)

  O-1 - Second Lieutenant (2LT)
  O-2 - First Lieutenant (1LT)
  O-3 - Captain (CPT)
  O-4 - Major (MAJOR)
  O-5 - Lieutenant Colonel (LTCOL)
  O-6 - Colonel (COL)
  O-7 - Brigadier General (BGEN)
  O-8 - Major General (MAJGEN)
  O-9 - Lieutenant General (LTGEN)
  O-10 - General (GEN)
  O-11 General of the Army (GOA)

Navy Ranks:

  E-7 - Apprentice Seaman (AS)
  E-6 - Seaman 2nd Class (S2C)
  E-5 - Seaman 1st Class (S1C)
  E-4 - Petty Officer 3rd Class (PO3)
  E-3 - Petty Officer 2nd Class (PO2)
  E-2 - Petty Officer 1st Class (PO1)


  E-1 - Chief Petty Officer (CPO)
  
  O-1 - Ensign (ENS)
  O-2 - Lieutenant Junior Grade (LTJG)
  O-3 - Lieutenant (LT)
  O-4 - Lieutenant Commander (LTCDR)
  O-5 - Commander (CDR)
  O-6 - Captain (CPT)
  O-7 - Commodore (COMM)
  O-8 - Rear Admiral (RADM)
  O-9 - Vice Admiral (VADM)
  O-10 - Admiral (ADM)
  O-11 - Fleet Admiral (FADM)

Marine Ranks:

  E-7 - Private (PVT)
  E-6 - Private First Class (PFC)
  E-5 - Corporal (CPL)
  E-4 - Sergeant (SGT)
  E-3 - Platoon Sergeant (P/SGT)
  E-2 - Gunnery Sergeant (GY/SGT)
  E-1 - First Sergeant (F/SGT)
  E-1 - Sergeant Major (SGTMAJ)

  O-1 - Second Lieutenant (2LT)
  O-2 - First Lieutenant (1LT)
  O-3 - Captain (CPT)
  O-4 - Major (MAJOR)
  O-5 - Lieutenant Colonel (LTCOL)
  O-6 - Colonel (COL)
  O-7 - Brigadier General (BGEN)
  O-8 - Major General (MAJGEN)
  O-9 - Lieutenant General (LTGEN)
  O-10 - General (GEN)

Weapons:

  Sub-Machine Guns:

    M1 Thompson
    M3
    M50 Reising
    UD-M42

  Rifles:

    M1903 Springfield
    M1 Garand
    M1917 Enfield
    M1941 Johnson
    M1 Carbine
    M1A1 Carbine
    Marlin M1894
    Winchester M1894
    Winchester M1895
    Remington M8

  Shotguns:

    Winchester M1897
    Winchester M12
    Browning A5
    Remington 31
    Stevens M520-30
    Ithica 37/M37

  Flamethrowers:

    M1A1 Flamethrower
    M2A1 Flamethrower
    Ronson Flamethrower

  Infantry Machine Guns:

    Lewis Gun
    Browning M1917A1
    Browning M1918A2
    Browning M1919A4
    Browning M1919A6
    M1941 Johnson LMG
    Browning M2HB

  Anti-Tank Guns:

    M1 Bazooka
    M1A1 Bazooka
    M9 Bazooka

I hope you liked it! If you want more information on ranks, you can look at my Trello board https://trello.com/b/idMUKMMv/usm1940-ranks.