I'm not sure what dimensions 2,3,4,5 or 6 are, when i see those the are usually refering to Dunhills which I own none. for the past year or so, i'm favoring big bowls, at least 7/8 to 1" size, I always say, If I can get my thumb in the bowl it's a good size. as far as depth, at least 1 1/2" min. I don't like the shallow bowls. I do own pipes that fall into the catagory of small size bowls and depth, I don't smoke them but in the near future I'm gonna take my hand at smoking flake and VA blends and my smaller pipes will be used for those.
For me the bigger bowl, makes the tobacco burn easier and allows for a better flavor and smoke.
For me the bigger bowl, makes the tobacco burn easier and allows for a better flavor and smoke.