Really? Because in my job as Box Office/Concession/Usher at a major Movie theatre, I came across numerous 1999s!
I too have seen what I'd estimate to be 250+ 1999 SBAs in bank rolls, change machines, post offices, etc.
Yes of course they could. The same thing is done with most all coins and always has. BU is merely a descriptive term, as long as there is no wear on the coins they remain BU.
I have no doubt - they get into circulation the same way the half dollars and Sackies dated 2002 and later do.
I am not an authority on this, so I am not sure by any means, But, I don't think 1999s were sold in rolls or bags. Also, the Mint struck them because they ran out of dollar coins prior to the Sacky being issued. I get 1999 SBAs on occassion, and my assumption is that they were released for circulation.
The 1999 SBA's were a circulation coin and they were released through the Federal Reserve to banks for circulation. the reason they were struck was because there was a consistent draw down of SBA from the Fed by banks of about 5 million coins per month for use in Mass transit systems such as subways etc in the large cities. In Sept of 1999 this small monthly demand finally exhausted the SBA stockpiles. The problem was that this demand was continuing and they could not strike the Sac dollars until 2000. So they had to strike a supply of 1999 SBA's to tide the Fed over until the Sacs came along in January.