reloading win 296 and 158 JHP for .357 Mag

I have been reloading for over 20 years and in every manual I have on Winchester data (including Winchesters) has always listed the reload data for .357 Magnum with a 158 JHP at 16.6 grains with the caution of never loading a lower charge.

Today 10-10-2009 I happened to spot a new load data manual while buying a new supply of Winchester powders. This 2009 manual now lists 16.7 as the max load and suggested I get more data on the internet site.

In logging onto their site I now discover that in the 2009 load data it lists 15.0 as the minimum charge and 16.7 as the maximum for this powder/bullet combination.

My questions are as follows:

Since I still have some 296 dating back into the mid 90's I need to know if the Win 296 powder formula has been changed or is it still the same powder? Is it safe to use the older powder at the new load specs? The powder is still good as it has been properly stored.

What is the reason for the change in reload data since Winchester was always concerned about squib loads when loading less than 16.6 grains of Win 296. (Yes I am using Mag primers)

Thanks for the attention on this. I have always been a cautious and attentive reloader and just want to be sure.



  • 44shotdoctor44shotdoctor Member Posts: 178 ✭✭✭
    edited November -1
    Myself I have asked this question if old powder and new powder has changed over the years? Everyone that answered said old powder is the same as if you just bought it today. As for loads for this round the newer manuels are not near as hot for this load. Example a Sierra from the 80's shows 15.1 to 16.6. And the newest Speer available shows 13.2 to 14.7. I even show a load to 17.3. I try to view all my manuels and try to find common ground on a round. And I consider safe. I think a lot a difference comes on gun used in testing. Good Luck
  • Rocky RaabRocky Raab Member Posts: 11,036 ✭✭✭✭
    edited November -1
    The difference came about when Hodgdon took over the sale of Winchester powders. Hodgdon always allowed you to reduce H110 (the exact same powder) by no more than 3%. I suspect that as they are now writing the rules, they simply made them the same for both brands. The powder itself did not change.

    Now, a full grain is more than 3%, but I doubt it represents a problem with squibs - especially under a 158-gr bullet. With a much lighter bullet, it might get iffy.
    I may be a bit crazy - but I didn't drive myself.
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