The difficulty here is that a springer can be so consistent that the other variables make it difficult to get meaningful data.
Chronos typically are +/- 1%, even working on .25% still introduces 4fps spread.
Pellet weight. The old jewellers scales are ok for weeding out light and heavy pellets, but they are not super accurate. Just because it gives you an answer to two decimal places doesn't mean much. Re-weigh that same pellet 5 times and see the variation.
You would need to shoot very large sample sizes, and the pellet weight problem will always be an issue.
In the real world, shooting 30 shot strings with pellets straight from the tin is all you really need. Any spread below 10fps is good and will have little or no effect on accuracy IMO.
My 97 gave a spread of 6.8fps and a SD of 2.4fps over a 30 shot string (Daystate 4.52). I don't need to know any more. It's consistent.