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Fig. 1

View picture in original size
Fig. 2

Bulova 6BKC (Aurore-Villeret 123)

manual wind
sweep second

6.75 x 8''', Dm= 15.3 x 18.0mm
Do= 15.3 x 18.2mm
F= 0.8mm
T= 1.7mm
17 jewels
f = 18000 A/h
power reserve 40h

Balance staff U2817

Stem W2083

Mainspring / battery
Zf928, 1.35 x 7.5 x 0.08 x 250mm

1.10 x 0.60 x 0.18mm

Comments about the data

Aurore-Villeret 120, Bulova 6AH, FHF 120 and the many variants of these calibres are quite equivalent. Exchangability data are contradictionary in the various movement registers. Therefore here only calibres are listed which are mentioned in several registers as derivatives of these base calibres, or which could be checked for equivalence.
The Bulova calibres have design details which are not present in the FHF calibres. So the ebauches came probably from Aurore-Villeret.

(Swiss, if not else mentioned)
Breguet hairspring, 1 crown-wheel screw, short edges straight:
6AM, 6AN: 17 jewels
6AMC: 17 jewels, sweep second
6AZ: 17 jewels, minor layout modifications
kurze Kanten rund:
6AH: 17 jewels
6AK: 21 jewels, U.S.A.
flat hairspring:
6BK: 7/17 jewels, new balance
6BKC: 17 jewels, new balance
new bridge layout:
6BA, 6BC: 17/21 jewels, U.S.A.
6BAC: 17 jewels, sweep second, U.S.A.
6BE: 17 jewels
new balance:
6BD, 6BL, 6BS: 17 jewels
6BDC: 17 jewels, new balance, sweep second
6BO: 17/21 jewels
6BOC: 17 jewels, new balance, sweep second
Kif-Flector shock protection:
6BM, 6CA: 17 jewels
6BMC, 6CAC: 17 jewels, sweep second
2 crown-wheel screws:
6CF: 17 jewels
6CFC: 17 jewels, sweep second
mobile stud carrier, Kif-Ultraflex:
6CL, 6CT: 17 jewels
6CLC, 6CTC: 17 jewels, sweep second
6CLC2: 17 jewels, differing orientation of the hairspring, sweep second

Example, year: signature; shock device
1949: 49, BXW, Bulova Watch Co, 6BK, Swiss, Unadjusted, 7 Jewels
(Bulova 6BK, no second)

Not for Sale!
The movements presented in this caliber finder are not for sale. This is only a data sheet for identification and evaluation of the movement calibre, as well as for approximate dating.

bidfun-db 21.3 © 02-08-15, mtr-Ranfft

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