I would love to answer the question, but more information is needed. Wtih two guns and cocaine there are a lot of issues going on here. How much cocaine? What is his record like? Is he a convicted felon? He is looking at two levels for the firearm under the guidelines and no safety valve benefit if the gun was possessed by him or possibly some other co-conspirator. Without an amount of cocaine in the question, or more detail, I cannot give you a concise answer.
Typically, a detention hearing will be held to determine whether he can remain on recognizance awaiting a revocation hearing. The district court will set a court date and the p.o. will submit the person's PSR to the court again with a recommended guideline range based on the violation. I haven't seen a scenario where someone remains incarcerated for an extended period of time for just drinking without a new criminal charge. But, I am not in your district in Washington; however, the guidelines...