A new reed follows a reverse bell curve. When it is new and first starts to crow it is hard to play and really sharp and loud. As the reed is shaved it gets weaker and starts to drop in pitch, the volume goes down and the tone gets softer. Further shaving will eventually reverse the results so that as the reed becomes very easy to play, it rises in pitch and the back D sounds flat. Opening the reed a bit makes it harder to play and flatter - the opposite of when you started. (Sky)

How far the reed protrudes from the chanter also affects the relative distances between the reed and each of the holes, so that the higher holes are affected more than the lower holes. If a reed is too far out, the back D will be flat to the lower notes and vice versa. (Britton)

The size of the shaved portion of the blades: The more it is shaved the flatter it plays. It is important in any case to stay within a general V or U shape. Where it is shaved will affect certain notes, especially the back D. (Britton)

Variable that affects pitch: The internal volume of the reed in relation to the length. This affects how the octaves are in tune with each other. The more internal space, the sharper the second octave will be to the first. This is affected by the diameter of the staple, how much the staple is flattened, and how open the lips are. The length of the blades also affects this in two ways. First of all, the shorter the reed, the greater the inside volume will be in relation to the length. Secondly, the tip of the lips is where the smallest amount of volume to length is, thusly, by removing a bit off the length, the average ratio of volume to length is raised. If there is a collar on the reed, closing this down would lessen the inside space, and vice versa. (Britton)

The amount the blades are shaved. If the blades are too long and/or too wide and shaved a lot, the reed will be ungainly, playing easily in the first octave, but resisting the second octave, perhaps "breaking" and/or being flat on the back D, and having the tone of a duck quacking. This can be alleviated by trimming off the end of the lips. This may leave the lips a little thick so that further sanding may be necessary. A small burr is often created when the lips are trimmed. This can be burnished off by pressing the lips of the blades together with the thumb and forefinger and flexing back and forth pushing the staple in one direction then the other. (Britton)

The amount the lips are open: The closer the lips are the easier it will be to play. Also, the angle at which the staple is flattened will determine the angle at which the blades are pressing on one another and consequently the opening of the lips. (Britton)

The shape of the opening at the lips. Sometimes the sides collapse after a while so that it becomes harder for the middle portion of the blades to make contact. The pressure needed becomes greater and the tone and volume are reduced. This can be alleviated by using a small slip of sandpaper approximately the size and shape of the head of the reed. When this is inserted and moved in and out, the sides close to the edge naturally exert more pressure on the sandpaper and push the middle portion of the blades away from the sandpaper. The tapered shape of the sandpaper ensure that a step isn't created at the edge. The outside can be sanded to maintain full uniform thickness at the lips. (Britton)

I have found with my chanter that the bridle position and opening at the lips cause the differences between the two octaves. If I slide the bridle toward the lips a bit, it will bring the 1st and 2nd octave E's into tune when the 2nd octave E is sharp. Moving the bridle up also opens the reed lips so then I must then squeeze the bridle together to close the lips. If I close the lips too much at this point then my 2nd octave E goes sharp. It's a trial and error adjusting process til I find the right combination of bridle position, opening at the lips and seating height. I'm assuming that your scrape and sanding are all in order. Because if your reed is too thick then your octaves won't line up. Sanding and scraping will flatten the reed and make the 2nd octave easier to reach giving you more ability to control tuning with pressure. Sand and scrape too much though will send it too the graveyard. I tried a larger staple size once but it didn't work for my chanter. Also remember that your 2nd octave E should play at or very close to the same pressure as your back D. Ideally the same pressure. (G. Burman)

A staple that is too narrow will produce a scale of notes that is flat in the upper octave. (Hegarty)

A staple that is too wide will produce a scale of notes that is sharp in the upper octave.

The degree of opening of the eye (of the staple) seems to affect the G note. (Hegarty)

The extent of the eye opening and flattened portion of the staple may effect overall the high octave, and the eye may also effect low G and high octave G more than some other notes. (Hegarty)

Further insertion of the staple into the reed will sharpen the high A and B relative to other notes. (Hegarty)

Reed is sanded too much. (Hegarty)

Overall volume of the reed is too small. (Hegarty)