I don't know anything about ballistics so forgive me in advance. This just came out today. MAC suggests that subsonic will tumble out of the Rattler creating better terminal ballistics vs. zipping right through from the 9inch. No idea how watermelons stack up to ballistic gel or human tissue, but I was thinking about a Rattler or a 9inch AR pistol lately and I thought it might be interesting to discuss the ballistics of it all (subsonic and supersonic).
https://www.youtube.com/watch?v=rTxhMFqzqV0