To the best of my knowledge Pioneer never used block meerschaum for its cups. Always pressed. That said, they were regarded as the best pressed meerschaum anywhere; and, believe it or not, they were renowned for their ability to color. They would turn a mottled pinkish color before going amber and cherry.
A Pioneer gourd calabash is probably the most carefree pipe you could own. Unless it is producing a horrid taste, or it got blocked-up and doesn't draw, I would not clean the interior. If you think the interior looks just awful, be advised that it looked that way after only the first ten smokes or so. Never a pretty sight -- but no cause for alarm.
It's the one pipe in your collection that you can smoke 10 times a day, every day, and never tire it out. Unwarranted cleaning can only increase your chances of loosening the ferrule glued into the neck or, as was mentioned, the cork. All you need to do is remove and clean the stem after every smoke, and rub a sparing dab of lanolin into the cork once every few years to keep it supple. (Drug stores sell pure lanolin by the brand name Lansinol)
