Look closer at the serial #. Are you sure that the prefix is a B, or is it an H. I have no reference to a "B" prefix. If it is an "H", it would be a 1954 Standard Weight, 12 ga.
Remington also made a model of the Auto-5, which was very similar to the Remington mod-11. The Remington Auto-5 was marked with the Browning logo and started with Serial # B5000 through # B43129. If this is the case, you have an "American Browning" Auto-5 in 12ga made by Remington.
Hope this helps,
Last edited by masterPsmith; 01-09-2010 at 08:24.