Ok Airborne, here goes:
There were what I call 3 groups of Model Marked Heavy Duties
The first group of Model 20 marked guns consisted of 14 guns-11ea 4" blue and 3ea 6.5" blue and are found in the S192000 and S211000 serial number range. These were 4 screw models.
The second group of Model 20 marked guns consisted of 34 guns, all 4" blue and found in the S241000 serial number range. These guns, in my opinion should have been marked Model 20-2 since they are all 3 screw guns.
The third group are Model 20-2 marked guns and consisted of 50 guns, all 4" Nickel in the S255000 serial number range, all 3 screw and went to Austin PD.
A total of 98 model 20s so far!

I hope this clarifies the numbers

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