W-231 and HP-38
The Hodgdon versions of those powders were from bulk lots and blended to Hodgdon's specs. The powders were exactly the same powders except that Hodgdon allows more variation from lot to lot of their powders than Winchester did of their powders. For example Winchester may have have allowed say 3 percent variation and Hodgdon may have allowed 5 percent. They were the same powders, just allowed burning rate range was different. There could be complete overlap or there could have been some Hodgdon versions that were out of range of the Winchester powders. The differences would show up in load guides just like lot to lot variations and using the load data interchangeably most likely the end user wouldn't be able to tell any difference that they don't notice from can to can. I have interchanged their load data for many years. Before Hodgdon got the deal to distribute the Winchester powders W-748 was fairly tightly controlled in burning rate from can to can. Now there are often fairly large differences from can to can and it doesn't have Hodgdon powder match. The differences are more noticeable in rifle powders. The powders that are same powders only differed in looking like larger lot to lot variations of the same powders, which is what it was. It has been known they are the same powders for a long time. Hodgdon bought IMR powders and their lot to lot variations have increased since.
