I've been told that they stopped using manganese with the onset of WW1, as it was needed for munitions. That being the case, it would date this bottle to pre 1918
I'm a rather new collector myself but that aqua bottle that has AB on the bottom is an old Anheuser-Busch bottle I have one and did a lot of research and found out that's what it is mine appears to be identical to yours and is circa 1915
I'm in the Fort Lauderdale area in South Florida and I've never dug before but I'm more than willing to lend my labor for a bottle or two should I find one