Not real sure I can....
As for standard production 2 1/2", 4" and 6" M19's, I'm not aware of any real variations in barrel profiles, however, there are other unique configurations related to special orders and/or PC production 3" models. You will see different shapes and profiles in the 3" guns.
There is a fixed sight variation that was produced for export to France, this is a 3 inch gun.
Also, the K-Comps and other PC versions have their unique profiles.
And lastly, the Model 19P made for export to Peru, had a fixed sight frame, and both 2 1/2" and 4" barrels, but not sure the barrel profile was all that different from standard versions (except for the front sight base).
Here are a few pics of what I can provide:

Early M19 with 3" barrel, while obviously special order, I believe this to be standard "weight" :


Performance Center K-Comp:


Another PC variation with 3" barrel:


Early - Pre Model numbered Combat Magnum:


Model 19P 4":
Note - this is without a sight ramp "base", but I believe the barrel profile is the same as a standard 4" M19:


Model 19P 2 1/2":


Hopefully this helps....

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.............SmithNut