I started almost 50 years ago with a 12 gauge Remington 11 - a knockoff on the A5. Over the years I have owned four 12 gauge A5's, shot many, many ducks with them, and for some reason, wandered into O/U's and hadn't shot autos very much for years. I recently bought a really nice used A5 Light 12 and last week took it out for sporting clays. I was somewhat startled at the "clink -a-chung" mechanical recoil, even though I knew what was coming and expected it. I was pleased with how well I shot with it and that unique A5 recoil was like a reunion with an old friend. Although I didn't shoot my other A5's for several years, I just can't be without one. They are classics and there is good reason why they led the pack for the better part of a century. They are fine guns.
You need to know how the friction/recoil system operates to make sure it is set up appropriately for the loads you are using, but it's very simple. (Brithunter, I have seen enough of your posts and firearms - I know you know that.) I think that most of the modern gas guns are really great, but the old humpback will still get the job done. I believe I have a reference chart on the serial numbers, but will have to search for it. Let me know if you want me to look. I don't recognize the "Acier".
Addendum: I Googled "Acier Browning" - got the following -
http://wiki.answers.com/Q/What_is_a_Browning_Acier_Special_12_gauge_c12_px_Belgium_and_it%27s_value