That's a little too much work for me. I just take a 4" barreled gun (as the standard) and work up the load then shoot in 2", 4", and 6" and note any change in POI. In my experience, at distances self protection, 10 - 12 yards, the difference is insignificant. For special purpose loads, such as bullseye at 25 yards, I work up specific load for each gun.

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H Richard
SWCA1967 SWHF244