Based on the below pictures, can someone please give me the date of manufacture for the cartridges pictured, and also explain how they arrived at the date?

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Terry Lester

Because of the K, I believe it is 1935.

http://gigconceptsinc.com/files/Olin2.pdf

Definitely between 1935 and 1955. From the reference Max posted it should have been Sept. 1953. It indicates the first two numerals are the year, reversed!

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Gunsmithing since 1961

Buddy had some of that. Leaded up his 357 like crazy. And was a lot hotter than the stuff we get today. Frank

The large primers were only used for a few years after introduction in 1935, so it’s definitely pre-WWII.

Another identifier is the “Winchester Repeating Arms New Haven Conn” line printed on the bottom front of the box. That was removed in 1939, when they added “Division of Western Cartridge Company” to the side.

The box printing changed again in 1945, when the side printing was changed to “Olin Industries”.

Nice find!

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"I also cook."

I don't think it is a coincidence the numbers after the K are 357. Also you have the large primers as were mentioned. I think this is very early ammo.

The K357OT is a factory stock number. The actual date of manufacture would be the hand stamped number inside the end flap. What I can see appears to be only part of the number. Winchester/Western date codes have been deciphered, I have a chart from the International Ammunition Collectors forum. Basic format for Winchester before 1957 had the first one or two digits as the month followed by the last digit of the year of production. Then a space followed by the date of the month. This system repeats every ten years.

That's interesting information. I have often read that the 357 magnum in the 1930s were often loaded hotter than the stuff you can get today. It is interesting to read some first hand reports.


I also raised a historical question in my mind. When were the 357 mag loads reduced in power ?

Well I finally got the ammunition in hand and was able to take a better picture of the hand stamped number inside the end flap. It appears to be 111 26 or 111 20; the last digit is stamped in the crease and so is not fully decipherable. Below is the picture…..


So using the Winchester format quoted above I would translate the date code on this box to be November 20 or 26, 1941.

The below pictures are taken from the informative article entitled “Dating Pre-War .357 Magnum Ammo Boxes” written by David Ballantyne and published in the Fall 2014 S&WCA Journal……



So the interesting and/or confusing part of this is that the box of cartridges I just received is the 1935 style (as can be seen in post #1 above), not the 1939 style, but yet the Winchester date code indicates a manufacturing date of November 1941. Perhaps Winchester, like S&W and Colt, never threw anything away and continued using the 1935 style boxes concurrently with the 1939 style boxes until all of the old style boxes were totally depleted.

Does anyone have a different theory?

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Terry Lester

I had some handloads that were packed to original specs...hot, hot, hot! Had to wait until they cooled down to extract them from my M28.

I think most published figures in the '50s and '60s were still around 1450 fps muzzle velocity with a 158 grain bullet. Perhaps the reduction was in the '70s?

I guess you could say that the 357 Magnum has been slowly downloaded since day one after the first complaint of noise and recoil; in Douglas Wesson’s book “Burning Powders,” he states the 357 Magnum running at 1515fps and 812ft-lbs, which be out of the 8-3/4 inch barrel in 1935.