Instead of copying track and deleting data I use this Reaper actionphotonic wrote: When the arrengment is done, I copy this MIDI track to each drum sound from the synth and delete all midi notes which do not belong to the specific drum sound. E.q. I delete all data exept the kick data. On the next I delet everything exept the snare and so on.
Item: Explode MIDI note rows (pitch) to new items