4 seconds per day... how about your Royal Oaks?
My 15400 Royal Oak is gaining about 4 seconds per day. I believe COSC standard is -2/ 6 seconds per day so I think it is within standards. How accurate are your Royal Oaks?
In that range. I have had very good luck with 3120 based Offshores
My 15202 ran somewhat fast after receiving it many years ago. A service corrected the timing.
Very easy. The minute hand was a minute ahead in about 2 days.
Wait a week and it becomes quite obvious. I dont recall the exact reason, it was not magnetized but something different.
