Should I bore out my blowstick?

There are three problems that people try to solve by boring out the blowstick:

Lack of reliable operation with a leather flapper valve, or
Repair a crack due to blowing into a dry blowstick, or
Insufficient air flow through the blowstick.

As background - please don't ever blow into a dry bagpipe. Moisture from your breath with swell and crack the blowstick and/or stock within minutes. How should I bring an old bagpipe back into service?

I've seen a couple wooden blowsticks that have been so weakened by boring that the upper threads eventually broke off. Further problems are created when one tries to place a flapper valve on the enlarged hole in the bottom and it doesn't seal well. "No problem, I'll use a Little Mac", you say. Little Mac's are held in place by friction and I've seen several blowsticks split by the constant wedging action of the Little Mac into the bottom of the blowstick. If you've bored out the blowstick, the walls are thinner and it's easier to split.

If the goal is to eliminate the problems of reliability inherent with a leather flapper subjected to occasional use, Naill (and other people) makes a very nice brass and rubber flapper that is superb. It fits right where the original leather one went and costs about $3.

If the goal is to decrease the resistance of my blowstick, my suggestion would be to purchase an Airstream blowstick with integral valve. In the long run, the Airstream blowstick with integral valve is a wonderful investment. The contoured mouthpiece is also a lot easier on your teeth. The only maintenance is to replace the latex rubber piece about twice each year. The only downside to this is that the all-black blowstick might not exactly match your bagpipe. Go to a hobby shop and get Testor's Model Master enamel in the color called Light Ivory.

If you feel that you simply must bore out the blowstick you have, I'd suggest that you line the bore of the blowstick with brass tubing available from most hobby shops. It provides strength, moisture control, and a nice seat for the Naill flapper valve. You can find detailed instructions here.