A-591 was a transition or experimental product of A-581's next production of 611 series. The factory modified the 581 movement for non-screw balance or anti-shock unit features. Somehow, may be the accuracy can’t met the factory standard, it stopped its production and that’s why not much of 591 had made.
The prototype which I have, it has a non-screw balance wheel with early type regular index. The balance wheel is so rough; I suspected it was hand made by the factory maker.
The prototype which I have, it has a non-screw balance wheel with early type regular index. The balance wheel is so rough; I suspected it was hand made by the factory maker.
