[lurkingknight]

there are a lot of complex factors in trying to calculate joule creep/overvoluming, so it's more time saving to just do it with trial and error. The progression is not linear and highly dependent on cylinder volume vs barrel volume, projectile weight and a lot of different factors on how the air charge is delivered. I've read about people trying it by just changing barrels and the chart was definitely not linear and they couldn't account for all the variables in the math to equal the end result values they were seeing. The only thing they could replicate was similar results, but not predict exactly what the results would be, so they know the effect exists, but don't have the math to solve it.

It comes down to if it shoots the correct fps with one barrel for one use, and the correct fps for another use, then you are ok, don't ask anymore questions unless you want your brain to explode.