Chris Brown's Gotta Stay Away from Karrueche's BFF in New Restraining Order

Chris Brown now has to stay away from his ex-GF Karrueche Tran's BFF too ... after the singer allegedly threatened to gun him down and sent gangsters after him.

Joseph Ryan La Cour says he's been on the receiving end of Chris' rage because he stands up for Karrueche while she fights to keep Chris away from her.

In docs -- obtained by TMZ -- Joseph says Chris has been saying things like, no matter where they go "he will find us and shoot the place up."

Joseph gets specific ... pointing to an incident at Diddy's Super Bowl party -- in the docs, he says Chris got in his face and said, "it's 2017 ... Ima f*** you up every time I see you so you better get the f*** out of here before I lay your ass out."

At the same party, Joseph says Chris threw a drink at one of his friends and told her, "Move bitch, we aren't friends." It was right around the time of that party when Chris posted a video vowing that if he couldn't have a woman he wanted, then no one could.

Joseph also claims Chris sent guys after him ... and believes they have gang ties because they threw around the word "blood."

Chris has been ordered not to harass Joseph and to stay at least a football field away.