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.
I have to agree with the first answer. There are too many variables to give you a firm answer. If you've spent $20,000 on an attorney, then you should demand to receive every bit of information possible from them about your brother's situation. In the alternative, you can speak directly to another attorney and they will be able to give you a more specific idea once you outline the specifics to them.