after the tubes were welded they were sent to the grinder and it was there that the metal was removed, revealing the crolle or whatever desired pattern? Correct?
That is correct Joe. The forged tubes went to the grinders, for removal of excess material and smoothing of the barrels outer surface. But, the damascus pattern is not revealed until the tubes are etched in acid. Ground and finish sanded damascus appears just like a piece of mono-steel.
One thing that I really wanted to convey in this information, is the effect of grinding depth on the damascus pattern. Flat stacked layers, such as Crolle pattern is created from, are the perfect representation of the grinding depth effect.
Given that there was probably little to no communication between the smiths and the barrel grinders, the smiths had no idea what barrel profile the tube would be ground to. So forging to place what would become the outer finished surface of the tube at a particular depth was impossible. The grinders could not see the damascus pattern in the tubes while grinding and perhaps had no idea what the patterns in the tubes actually were. They were grinding to match the specified profile for that particular barrel. It seems likely that the damascus patterns in many barrels may not have been known until after etching.