I've got two Colt revolvers --Colt Python 6 Inch vintage 1977 and a Colt ".357" vintage 1960. Being a dedicated S&W man, these are my first Colt DA revolvers--I've been told Colt barrels runs on the "tight" side and after slugging them I can verify that!
On the Python's Cylinder throats I can push through (with moderate hand pressure on a wood dowel) a slug that measured .359 on a micrometer.
Then I slugged the Python barrel and the slug I took out of that measured at its widest point between the engraved grooves .355 on a micrometer.
On the ".357" Revolver the Cylinder Throats measure .3585
The ".357" barrel measured even tighter that the Python--the slug measured at its widest point between the engraved grooves .354.
I need some advice from cast lead shooters what size bullet would be choice for accuracy and minimal leading? .358 or .359? These guns will only see .38 Special Handloads -158 grain bullets or 148 grain wadcutters at standard velocity. Advice appreciated--thanks!