Something no one else has mentioned: I suspect that you may be packing the pipe a bit too tight. Here are three good rules to follow: (and I do mean rules!)
1. The tobacco should be drier than you think it should be.
2. The tobacco should be packed much looser than you think it should be.
3. You should smoke the pipe much slower than you think you should. Corollary to rule 3: if you can place the pipe against a baby's skin and the baby smiles because the pipe is pleasantly warm, you're smoking at the right speed. Any hotter and you're smoking too fast.
Follow these rules and you will have many more pleasant smokes with fewer relights, and a clean ash. Occasionally you will have some dottle, and you may find that it occurs with a certain pipe(s) or certain tobaccos. Also, if as you're smoking your way through the bowl, it stops tasting good and becomes harsh or bitter, put the pipe down--you're done with that bowl. When it cools, empty the bowl, clean it well, let it dry, and wait for your next smoke. By the way, your pipes should always be kep scrupulously clean, and allowed to dry thoroughly between smokes. I'd recommend at least a day if not longer. A clean, dry pipe smokes better.