A good friend and I were examining a Brit gun he was considering buying. There were some exterior pits within maybe 4" of the muzzle, and he decided to pass. Afterwards, as we were hashing over pros and cons, something occurred to us: How significant could those pits have been in that location, since people shoot guns all the time that have actual HOLES in the barrels in the same area (ported)? Answer: not very significant.