Just not a long ago I got me an estate Dunhill straight shell Briar form 70ies, and now I when I had smoked it few times I have noticed this very pipe is starting to show some symptoms of the slight gurgling, I checked the drilling and mortise, both these seem to be spot on(drilled something like 3,8mm-to 4mm)stem tenon is not bad either, and is far from being narrow, stem fits well and flush,whereas the airhole in the button is a bit small, I did enlarge it very slight,but that did not add any improvements, now are there any other remedies' which may help to solve this, does rounding/bevelling the stem tenon end a la Castello' bring any benefits?Thanks for the advice