For the OP, make sure you are rotating the engine in the same direction (CW) as you approach each reading. If you go too far and pass a reading point, then back up a bunch and approach the measurement point again in the CW direction. If you approach the same point going CW and then CCW, you will get different degree readings due to chain slack. The more the slack, the worse the variations.
What are you using as a pointer? Good trick on the 'solid' lifter.