Why does my chanter sound like crap?

[EagleJCS]

It takes time for the muscles surrounding the mouth to get accustomed to sealing the blowstick, either on the practice chanter or the bagpipe chanter. There's also an optimum pressure for playing the practice chanter - more than a recorder or pennywhistle, but not quite as much as the bagpipe. If you try blowing at the lower pressure, it will sound more like a (dying) duck call. Blowing at the highest pressure will 'shut off' the reed, and you won't get any sound out of it.

Regarding your particular chanter, Bren, you could have the holes cleaned up/rebored and have the internal bore smoothed/polished in order to make it into a decent-sounding chanter.

In regards to the flat/sharp pitch, there's a diagram online that shows what the pitch of each note is supposed to be when using a Korg-30 chromatic tuner. (As I'm sure you're aware, the bagpipe scale in not a chromatic scale). I can send it to you. There is also a tuner specifically designed to be used for the bagpipe (the HBT, or Highland Bagpipe Tuner), which will show the note to be in tune for the bagpipe scale (but it would be out of tune compared to a piano or guitar).