Quote Originally Posted by tiriaq View Post
Were LB barrels broached, or cut rifled using Pratt & Whitney type sine bar riflers?
If barrels were broached, only the actual cutting tooling would need to be changed. If a cut rifler were being used, there would be more work involved in resetting the machine, althought the same cutter would work for 2 or 5 groove.
The time required to broach 2 or 5 groove barrels would be the same. One pass, that's it. Whether there would be much savings in the tool room making 2 groove versus 5 broove proaches, I would not know. Using a sine bar rifler, a 2 groove barrel would require 40% of the machine time of a 5 groove barrel.
I would doubt that 2 and 5 groove barrels would have been produced simultaneously, although there could have been a transition period when tooling was phased in and out.
Wheaty has some broaches with multiple cutters...