Before separating the body make note of the position that the tension springs are in, on the aperture blade (the orange flange that holds the darts in). When reassembling, these need to go back in place.

Some blasters have "Do Not Tamper" stickers, you'll have to split those.

Then unscrew the 9 screws on the blaster body. I usually keep the screws in their screw wells, since they are different lengths, and they need to go back into the same spot.

Carefully pull apart the two halves of the body. Be careful the screws don't bounce out of their wells.