I have noticed on several watches, powered by the 1861 and 3201 and 3203 movements that these manual wind chronographs change their timekeeping behaviour.

The first one I noticed the FOIS was +6 to +8

A ck2918 was +8

Both of them became +2 to +4 after 2 weeks from new

A standard speedy pro was -3 from new and became dead accurate after some use

I purchased a used chronograph with a 3201 movement which was -4 for 2-3 weeks and this week I’ve wound it up and it’s also been dead accurate all week. Yet just a few weeks ago it was a concern at -4 to -5 as its co-axial chronometer

My timing method is exactly the same. My wear patterns are also the same, I always rest them crown down and I wear them on my right wrist.

This isn’t just 1 watch but it’s happening with at least 4 I’ve bought over the recent years.

Anyone shed some light on what may be causing the change?

Once they change from new they stay like this. Only exception is a couple of them were used and I can only assume a right handed wearer like myself creates a different orientation which is affecting the movement?