Charlie Sheen -- HAMMERED After Guns N' Roses Concert

Charlie Sheen -- a recovering everything-aholic -- hit the Guns N' Roses concert HARD this weekend ... REALLY HARD ... at least judging by the way he slurred through a Q&A with photogs after the show.

Sheen was leaving the Palladium in Los Angeles Friday night ... when he fired off a sloshy torpedo of truth about the band ... hinting they'd be BETTER with Slash.

We also asked about Sheen's favorite GNR song ... and we're pretty sure he cracked a heroin joke ... telling us, "Mr. Brownstone ... imagine that?!"

FYI -- Mr. Brownstone is a slang term for the drug.

As Sheen pulls away, one pap says, "I party like Charlie Sheen" ... to which the actor replies, "And you're still alive?!"