When I did mine it was really simple.
Two pins and the trigger is out.
Push the 4 square plugs out with a ground down allen key, they weren't under spring pressure.
The pressure of the spring is held back by the end plug which has a lightbulb type bayonet fitting into the cylinder. Place an M12 nut on the bench and take the spring pressure up by pressing the action down onto it, then it's a little anti-clockwise twist (no more than 30 degrees) to disengage the bayonet and the end plug comes out.