As long as you protect the blowpipe, the scales and darts stay in it and you protect them as well. Just in case you lose the blowpipe though, I'd recommend you pk with only a few hundred darts and a few thousand scales just in case.
You keep the attachments on the blowpipe if you're protecting the blowpipe itself, otherwise you'd lose everything. Don't risk the amount on darts you're not willing to lose.