The 12 year old in me giggles daily because my basket weighs 80.08.

Are you sure the diameter is really different or, like with Jon's, it is slightly out of round? Both would change how your dosing cup fits.

You say the shot times seem to be slightly different, mostly. To me that calls into question whether what you are seeing is real or simply random. Or maybe you are inadvertently, unconsciously affecting the results.

It's nice that you can't tell the difference simply by looking at them. That makes blind comparisons easier to do. You can mix up the baskets (like in a bag) and then pull shots from them without knowing which is which. Later weigh one to figure it out and compare with your shot times. Do that every day for at least a week, the more tests the better. It's easy to fool yourself with random combinations of events that appear to be a pattern. For example, you could throw dice twice and get snake eyes both times. Would that prove the dice are loaded? The odds are 1 in 72.

Thanks to all for the responses.

For now, I am satisfied with this information and am not inclined to launch a more scientific investigation....