AL45,
The Lee manual (2nd ed.) lists 2.894" as COL on it's drawing of the cartridge. It is a maximum and not a minimum. All cartridge drawing dimensions are normally maximums, not minimums. They have a unilateral minus tolerance and no plus tolerance, as is the convention in engineering drawings where it is more critical not take a dimension too far in one direction than in the other. In the case of cartridges, they have to fit in chambers, so it is more critical that they not be too big to fit, which prevents functioning altogether, than if they are a little too small, in which case they will function fine, though they may produce a little less accuracy than a perfect fit does.
In the case of COL, in particular, the maximum dimension is mainly to insure the cartridge will not be too long to fit in a magazine.
For the same reason of fit, chamber dimension drawing tolerances are done just the opposite way. The chamber drawing dimensions are all minimums with a + tolerance because a too small chamber would prevent functioning altogether, where a slightly too large one will not.
Just use your cannelure at the case mouth unless you have a feed problem with it.