Browning Double Auto Serial Numbers

I just bought a Double Automatic with a SN of A44xx and would like to date it. It doesn't have the rivets at the back of the fore end but it does have the rounded fore end and the short-radius round knob stock. It came with a 25.5' recessed rib skeet barrel and a plain matted 27.5' modified barrel. It makes a perfect companion for the steel frame one that I have with a recessed rib 29.5' full choke barrel. All barrels interchange. Do the serial numbers for both the alloy and the steel models run in sequence with only the letter prefix different or do they have separate sequences? I would also like to know when Browning make the various changes such as the fore end contour, stock radius, solid recessed rib to vent rib. I know that at some point they started to prefix the sn with a year but prior to that they are somewhat of a mystery.
Browning double auto serial numbers history

Browning Double Auto Serial Numbers Lookup

Import guns were in the same serial number sequence as all other Baby Brownings. The Browning Arms Company never referred to the gun as the “Baby” in their literature-instead, it was simply known as the “Browning.25 Caliber Automatic Pistol.”. Finding the Blue Book value of your new and used firearms, including pistols, rifles, shotguns, airguns, and blackpowder guns is easy with the number one source of gun pricing. This site provides values and information on firearms in a convenient online pricing guide format, and allows you to find out what your used guns are worth.