I prefer my pipes to be 4.0-4.3 mm. I have never opened or altered a pipe myself as I don't even own a drill. I buy pipes from makers who I trust and have had great expereience with. I bought an estate Tonni Nielson and it was too tight so I had my buddy Zack who is a pipe maker open it up for me and it smokes great now. I have no intentions of selling it but if I did, I would certainly tell whoever that I did have it altered. I bought the pipe based on a recommendation from a guy who loves Tonni's pipes, he might like a smaller opening, I don't so I would not buy another pipe from that maker. I have found over the years that some of the Danish artisans, do make their shank dimensions smaller than say Italian or American makers, it is the reason I no longer own any. They do not fit my smoking style so it is no big deal. Obviously there are plenty of people who do enjoy them.










