This is a discussion on Has Accurate Arms reduced their maximum loads over the years? within the Reloading forums, part of the Defensive Ammunition & Ballistics category; As I mentioned in previous threads, I'm just now getting back into reloading after a 15 year hiatus. When reviewing some of my old journals ...
As I mentioned in previous threads, I'm just now getting back into reloading after a 15 year hiatus. When reviewing some of my old journals I found some loads for Accurate Arms #2 that are extremely high pressure loads according to the current loads listed by AA on their website Accurate Powders Now everyone is prone to mistakes but normally I approach loads very diligently and note when one is pushing the envelope. However, I found a load I used back in 1996 using AA#2 5.4 gr, 124 gr XTP HP, seated at 1.05 @ 1150 fps. Current listings with the same powder and bullet show the maximum load at 3.6 gr for 938 fps with a pressure level of 34,518 cpu. I find it hard to believe I would have ever deviated that much higher and can only imagine the pressure levels such a load would produce. I don't recall having any problem with the load with primer cratering and such but considering my hot load was almost a full 2 grains higher than current listing has caused me great concern. I have a few of these loads still in the box and will use a kinetic puller to disassemble them to recheck the powder weight. My old Hornady manual didn't list AA powder but I had a flyer from AA that I got from my powder source which I can no longer locate. My question after reading some of the other previous threads about older loads is; did AA downsize their maximum loads or did I just really screw up with my conversions for my Autocharge on my press?
Yes the Powder companies adjust their loads from time to time on new batches of powder. This is done in closed bomb tests to determine burn rate and either copper crusher units or PSI to determine cartridge pressure is correct for the round involved. At the time you developed your load with that lot of powder the pressure was correct. The new lot of powder must have tested at a faster burn rate reaching peak pressure with a lessor loading density. The smaller volume of powder burned in the same volume results in lower velocity even though the pressure is the same as previous loading density.
All this works from the recommended SAAMI specs for the cartridge involved.
There is also the possibility the fire arm manufactures may have reduced the pressure limits because of field failures.
Your previously loaded ammo is likely OK as it was loaded to the specs available for the powder in question at the time. However, why chance an injury or damage a good firearm?
At the least, I would call Accurate and ask the question.
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