Heh plenty thanks

There will be a whole host of new info coming out regarding them in the next incarnation of the CSM codex out in the not too distant future.
Waaaaaay back in the day they began life as the Tiger Claws chapter headed by a megalomaniacal chapter master named Huron Lugft. Huron led an uprising against the Imperium on a planet named Badab (hence the epithet \"Tyrant of Badab) enlisting the help of a couple of other chapters in the process. The rebellion was put down and that was it for a while.
Several years later GW ressurected the storyline, renaming the chapter the Astral Claws and fleshing out the information a bit. After his defeat Huron was badly injured by a melta weapon and had half of his body melted off. Being a superhuman Astartes however he survived and had it replaced with bionic bits. He took the remains of his disgraced chapter and fled to the Maelstrom (baby Eye of Terror) and renamed them the \"Red Corsairs\". The Corsairs are a refuge for renegade Astartes from any chapter. New inductees paint components of their original armour red to signify their new allegiance. They basically act as pirates, raiding Imperial shipping and saying Yaaaarrrr a lot lol