Try the gun parts corp, and also keep watching Gunbroker.com in the magazine section of firearm accesories. It may take a while as these are not easy to find. I would also suggest doing a Google search.
The pistol is actually a Model of 1900 made by Fabrique Nationale (FN) and designed by Browning. These were used extensively during WWI by trench sweepers and Belgian/French officers. Modern repro magazines for them are available from gun parts sources (try numrich online). Good luck. FYI, Brevete means "patent" and SGDG stands for "Sans Guarantee Du Government," which means without the guarantee of the government. The name of the gun is FN Model 1900 or Browning "Old Model."
No
50-350 usd
From Browning's website - "allowing the shooter to retain shells in the magazine and eject a shell from the chamber without feeding from the magazine."
no
No
No
Requires a gunsmith.
No
No.
If this is a Browning rifle, contact the Browning Parts and Services Dept. at the link below.
No the meaning of browning bdm means browning detachable magazine,while the browning da means (double action) and sa means (single action) in reference to browning handguns.