Drill a small hole through  the back of the bolt where the hammer pin goes

then sand it down to take the burrs off . This just make it a little EZer the get the bolt on/off the hammer pin

Now put the hammer on and try to put it in the gun if it sticks or gets hung up in anyway ..........

.........file the bottom of the back of the bolt where the hammer pin goes in flat (not to much) then sand any rough edges down

Doing this puts a little space between the hammer and the bolt so they have room to move a little so they can lineup straight in the gun.