Originally Posted by
juvela
Thanks very much!
Had been leaning toward Giostra but wanted additional evidence; you have found it.
OP's headset would not have had the Magistroni name as Giostra ceased using this in 1965 and launched the OFMEGA marque in 1966. So if one could find a new one of these in the box contemporaneous with the blue frame it would be so marked. Common for OFMEGA parts to bear no marque or else that of the bicycle manufacturer.
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Very interesting guys! At this point I'm going with the headset being original to the bike, and I guess from what your saying Juvela, the frame must be post 1965 as my headset has no markings of any kind.
That headset on Flickr certainly looks related to the one I have, I'd agree that mine is a Magistroni.
Unfortunately this frame didn't come with any stickers to give me a rough idea of when it was made. This helps place it a little at least.
Interestingly, it has a serial number on the underside of the BB which I've not seen on these old Bott's, plus I don't think it follows the numbering style used on the later frames. It also just doesn't look "right" to be factory stamped, I think its something someone did later to identify the frame. Perhaps with a hope of identifying it if it was stolen.