Scorch's answer schools mine to the middle of next week.
I had no idea parts were interchangable.
To remove the bolt:
1. With the bolt in the rifle and closed, move the safety switch on the back of the bolt to the top position (so that it is vertical)
2. remove the bolt from the rifle in the usual manner with the lever on the left hand side
3. the back of the bolt should now be able to twist off. Some may be harder then others.
That's how you access the firing pin. To actually remove the firing, have a look at this video as the actions will depict it better then i can explain it via text