I just used up the last of a can of IMR-4198 I bought in 1982 at Wal-Mart for $6.95. Even at 38 years, it still smelled right, looked right and delivered velocities 96% what it had when it was "young". It felt like I was saying good-bye to an old friend when I set the can down for the last time.
I move on to can of IMR-4198 I bought in the late-1990's for $16.95. Between the 4th Edition of the Hornday Handbook and the 8th Edition, maximum loading for IMR-4198 in .223 Remington dropped by a full grain (or more) while other powders changed far less dramatically (if at all). I don't know why the data changed, but I'm going to be using data from the 8th or 9th Editions with this "younger" powder.
Since I'm loading a lot more now that I'm retired, I expect to be using powders from the 21st Century by summer.
I move on to can of IMR-4198 I bought in the late-1990's for $16.95. Between the 4th Edition of the Hornday Handbook and the 8th Edition, maximum loading for IMR-4198 in .223 Remington dropped by a full grain (or more) while other powders changed far less dramatically (if at all). I don't know why the data changed, but I'm going to be using data from the 8th or 9th Editions with this "younger" powder.
Since I'm loading a lot more now that I'm retired, I expect to be using powders from the 21st Century by summer.