The 1907 Ithaca catalog indicates that the No. 1 Special had Cockerill steel barrels, the No. 1 Stub Twist, the No. 1 1/2 and No. 2 Damascus, the No. 2 Pigeon Krupp, No's 3 through 6 choice of Damascus or Krupp and No. 7 choice of Damascus or Whitworth. The catalog does not mention chamber length. I have two Minier models; a No. 2 and a No. 4, both 12 ga, and the chamber lengths are both 2 3/4.