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| Remarks: The 427 was a replacement for the earlier MST 417 Alarm claibre, with some internal refinements to the alarm mechanism. The calibres are almost identical externally, the only visible difference being a small hole in the alarm barrel bridge in the 417, near the hammer piviot. Most parts are interchangeable between the 417 and 427, the major difference is in the alarm cancel mechanism, with changes to the levers, springs and hammer. The 417/427 were a completely original alarm calibre design, featuring 2 barrels - main and alarm, both wound from the same crown. Similar in design to the Vulcain Cricket in that it uses a crown wheel rocker to switch between barrels depending on direction crown is wound. Roamer took out patents relating to the design of the special sounding back. |
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| Production period: 1955-1960 (est) |
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| Jewels: | 17 | | Beat: | 18000 | | Winding: | manual | | Manufacturer: | MST |
| | Hand sizes: | | Hour: | 150 | | Minute: | 90 | | Second: | 19 | | 4th hand: | 220 | | | | | Stem tap size: | N/A |
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| Variant: | | | MST 427 | 12''' (27mm) Alarm |
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| Common parts/Interchange |
| Balance Staff: | | MST part number: | 7480, | interchanges with MST: | 427 |
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| Multiple mainsprings possible: | | MST part number: | 1270 (Main) | interchanges with MST: | 427 | | Strength: | 0.1100 | | Height: | 130 | | Length: | 345 | | MST part number: | 1282 (Alarm) | interchanges with MST: | Nil | | Strength: | 0.825 | | Height: | 180 | | Length: | 320 |
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| Associated Patents: |
| CH321585 | Improved alarm hammer mechanism | | Deposited 1955, granted 1957 |
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| Watches in my collection with the MST427: |
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