This is an ORIGINAL firing pin for the 2nd and 3rd model Winchester 1873 lever-action rifles in the .44-40 or .38-40 caliber. If you have a 1st model you need part number 748 NOTE: Sometimes you will find first model bolts in a 2nd or 3rd model. If your bolt has a bushing on the face of the breech bolt projection then you will need the first model firing pin