If I go from back D (requiring solid pressure) down to bottom D (requiring low pressure), I tend to get a bit of a squawk. Is this a technique problem, or should I adjust my reed to make it a bit harder to play? If I make it a bit harder to play, it then makes getting up into the second octave, a bit harder too. 
yah ive found ya might have to close the chanter for a nanosecond, going from hi to lo d like that…adjust the pressure a squinch…(good practice for staccato back d’s 
)
& depending on the tune, sometimes a quick insertion of a secondary tone, (low a maybe low g) may assist, but its a matter of taste.
oh, & dont mess with the reed. learn to do what the reed likes to do,
then in time the reed will do what you like
sorry to be so…zen…but this IS the uilleann pipe after all 
yeah..i did the same thing for quite a while until I got used to adjusting the bag pressure.
It gets easier with practice.
I would not mess with the reed if the back D and the low D sound OK otherwise.
If it only squawks during the changeover, it is most likely the operator.
I sometimes do it going between second octave (G or A) down to back D because the pressure has not bled off yet.
Tim
Is your bottom D the soft or hard D?
Because if you’re going for the hard D, I don’t really know why you would need a pressure change at all, but if anything, you’d probably need a touch more pressure. As someone (who I forget know!) said, the hard D is a second octave note. So there could be a reed issue… I suppose.
But at any rate, the advice given is very good: Learn to play it, learn to adjust as necessary. These aren’t accordions or highland pipes… every note needs to be treated as special as it is.
I like to adjust my reed so that back D and hard D (achieved with an A cut) take the same pressure.
But if you are going from a back D to a low (not hard) D, you would need less pressure..right ?
I find this to be more so when playing with a reed that is closed up a bit.
The reed is easier to play but more likely to squawk on the low D.
Tim
Yes, but I (almost) never want a soft D, and I would say it’s pretty rare to hear a recorded piper choose it over the hard D, too.
Thanks everyone! The suggestion to adjust the reed to balance the back D and the hard D makes sense to me, because that’s just about where I’m at now. I figured it was operator error all along, I just wanted to make sure that my reed was good and that I just need to keep at it. That’s the toughest thing about taking on this instrument, is the NOT thinking in terms of highland piping.
Thanks you all!
yep. forget everything you thought you knew about bagpipes 
and gracenotes
took me years to stop playing doublings & thinking of cranns as birls. 
but now things are happily seperated into their own quadrants. 