To completely disassemble the 1200 C, you will need to know how to diassemble a Mauser 98 bolt, look for a tutorial online for that.
The trigger guard removal is probably the trickiest on these as you have to remove the cross pin for the mag release and in between the rails (if you look at the trigger guard from above with the release removed) you will see an Allen head screw. Remove this and you will be able to separate the trigger guard/mag assembly from the action, thus removing the stock.