Hang your target and place your rifle on sandbags. Remove the bolt and sight down the barrel and adjust the bags until you can see the target in the center of the barrel. Carefully look through the sights and see where they aim relative to where the bore is pointing. Adjust the sights accordingly. Repeat until they match. Test fire and fine tune as needed, but done correctly it will be surprisingly close. This has worked for me many times.
Link below will give some more details about the use of the sights.
Using the Sights of the Model 03-A3.pdf - Google Drive