Are powders changing?

[TedH]

I've been looking over some load data for the 257 Roberts. It's generally divided into standard (45.000 cup) and +P (50,000 cup) data. Looking at several sources of published data for the standard Roberts I see large differences in the loads. As an example a 100 gr. bullet with IMR 4831 shows max charge on the low end of 45.5 gr. in a Nosler manual from 1996, and a high of 49.2 gr. on IMR's website data. That's a huge difference!

So then I dug out an old Speer #8 manual from 1970 and it shows a max charge of 49.0 gr., basically the same as the "latest" from IMR's data. Just wondering if a powder has gone through changes over the years that would affect the data that much, or if it's just other differences in components and guns that were used during the pressure testing.

[Griff]

You might wanna double check that you're not looking a loadings for IMR-4831 and H-4831? They are DIFFERENT! Also, yes, there have been changes in powders over the years. While I'm sure the powder companies try to maintain consistency from one lot to the next, over the course of years there have been changes. It's one of big reasons to ensure you're using proper load data and still only work up to maximum loads in each and every load or gun you might own in a particular caliber. Also why, when you buy a new LOT of powder, you work up to your maximum load again.

Another of pesky little details that can harm your gun, not to mention you, if you fail to follow safe loading practices. This ain't a AIR gun you're loading for!

I might not have the credentials of a Terry or Mic, but I could use all caps if you think that would help keep you from blowing yourself or your gun up!

[TedH]

Yes, I'm aware of the differences between H4831 and the IMR version. I've been loading my own ammo for better than a quarter century and ain't lost any fingers or eyeballs yet, but I don't tend to hot rod my loads too much either. What I usually see is that the older data has higher maximum charge for a given load, and the current data is more conservative. Whether that's due to the lawyers or actual changes in the powder, I don't know or care. I usually try to abide by the latest data, but in this case it's the same as data from 40 years ago with lower charges in between there. Just though it was odd.

[earlmck]

Powder has remained pretty consistent. Main difference between new max loads and old max loads comes about from better pressure-measuring technology. The boys found out what pressures those old loads were really generating. A few cries of "holy goose poop" or similar, and they backed off their maximum loads a notch or two...

[TedH]

I think the more accurate pressure testing is true as well, which brings up the point of my original post that some current data is the same or in this case .2gr. higher than the 40 year old data, with data from 14 years ago nearly 4 gr. lower.

[TomD]

I remember reading something about how all sporting powders were milled from stuff dating from WWII. That was a while back that I read that, don't know if it was ever true, or how long it held up as true. Anyone know?

[Hobie]

Yes, I'm aware of the differences between H4831 and the IMR version. I've been loading my own ammo for better than a quarter century and ain't lost any fingers or eyeballs yet, but I don't tend to hot rod my loads too much either. What I usually see is that the older data has higher maximum charge for a given load, and the current data is more conservative. Whether that's due to the lawyers or actual changes in the powder, I don't know or care. I usually try to abide by the latest data, but in this case it's the same as data from 40 years ago with lower charges in between there. Just though it was odd.

Due to your experience then you must know that:
- different testers are working with different lots of components, i.e. brass, bullets, primers and powder
- different testers are using different firing platforms
- different testers are using different pressure measurement systems which have improved over time
- different tests AND take place in different climatic conditions, i.e. temperature and humidity, dittos for loading the ammunition

All these things can result in different results. I once did a review/survey/audit of many manuals' data on H110 and W296 and found that results were startling similar with some equally startling unexplained differences as well. Over time, some maximums have been revised downward because the new authors and publishers weren't comfortable in publishing the old data or discovered that the old data was incorrect.

[jdad]

My oldest load book is the Ideal #34 that dates to 1944. Loads are different, but so are the availability/introduction of new propellants.

What I found really interesting was how many cartridges had load data using 2400.

[Cimarron]

Powder has remained pretty consistent. Main difference between new max loads and old max loads comes about from better pressure-measuring technology. The boys found out what pressures those old loads were really generating. A few cries of "holy goose poop" or similar, and they backed off their maximum loads a notch or two...

That, and the fact that we are a much more litigious society now. It's the old "If I screw up who can I sue syndrome". That, coupled with too many lawyers chasing too few clients, has made any company that produces a product much more conservative and aware of legal ramafications of the misuse of their product.

[DPris]

Some powder formulations HAVE changed, 2400 being one.
Denis

[Kansas Ed]

One other factor that hasn't been mentioned yet was related to me by a customer service person at one of the powder facilities. It takes years to go through all of the different calibers, with pressure testing all of the different powders and bullet weights possible with each. The statement that was made to me was that generally the popular cartridges are focused on, with the less popular not looked at again for many years. If that is true then many of the cartridges we shoot on this forum probably appear to have more extreme differences, rather than gradually moving lowe0r, if it takes up to a decade or more to test again.

Ed