The BI, B1 W-I And I-I marks in the pictures by Garandrew and Mikey 51 are the marks aplied by the maker of the cas cylinder not the maker of the barrel. I am at work, so I cant check my referances, but I believe Garandrew's barrel is an Inland not BLC barrel because BLC started making barrels in about June or July '43 and the font on the INLAND MFG. DIV./ GENERAL MOTORS is wider and flater. They were markes BI on the barrel flat on the bottom behind the gas piston.
Hope this helps to clarify Inland vs BLC
Dave