Start with the gun unloaded and pointing down range.
Pull back the bolt fully and cock the rifle.
Push the brass loading shuttle with your left thumb fully over to the right.
Load the first pellet into the shuttle, then release the shuttle. Its spring will move it back to the left.
Push the bolt forward to load the pellet.
Now pull the bolt fully back and push the shuttle to the right again. Put pellet No.2 into the shuttle but do not release it yet.
Push the bolt forward and lock it, either into the rearmost cut out (safe) or fully forward (ready to fire).
Release the shuttle. It will not close fully because the bolt is in the way of the pellet. But it is closed enough for the pellet not to fall out.
After you have shot Pellet No.1, withdraw the bolt and re-cock. As the bolt comes back, the spring moves the shuttle over to the left, bringing pellet No.2 with it and positioning it in front of the probe. Closing the bolt loads the pellet into the breech ready for the second shot.