df06, FWIIW, choke effect is controlled almost exclusively by constriction. Therefore, you really must be able to measure it reasonably accurately if you want to know what choke a barrel has. "Accurately" means within 0.003". And that basically means a caliper type tool. You must be able to measure bore diameter just before the constriction and the minimum constriction bore. Compare diameter constriction to the standard choke constrictions for a name for the choke.
Patterning. Can't recommend it unless you are really invested in knowing. Even with the very best shells and guns, there is so much variability from pattern to pattern that you must have 10 patterns per load and barrel combination. Further, you must run a statistical analysis on all 10. The first pattern might actually be an average pattern or it might be an outlier - no way to know.
Fortunately, if you are willing to shoot the patterns, digitally photo them, and run them through the Insights program, you can know for sure. It is a lot of work, but it is real.
DDA
