Modern Data

[Lj1941]

I have been cross checking Alliant's modern data against 20 year old data in my Speer # 12. This data is for 45 ACP.To my surprise most of it is EXACTLY the same. I am sure that some powders have changed just a little along with primers. The old deal about using modern data appears to be a moot point-at least with Alliant. The 20 year old data was for Hercules powder! Comments appreciated.

 

[gamestalker]

I've seen a number of loads change, and even over a shorter time span. 7mm RM data has changed drastically with both RL19 and RL22. I've seen similar changes with other Alliant data from the old days.

It mostly the result of better and more precise testing methods. The old CUP pressure testing has become a thing of the past. I'm not going to put a lot of time into research into this thread, but yes, it has changed, and many of those changes have been quite significant.

GS

 

[wally247]

I've found the same from Alliant. At least for the cast handgun calibers I shoot.

 

[ArchAngelCD]

I have been cross checking Alliant's modern data against 20 year old data in my Speer # 12. This data is for 45 ACP.To my surprise most of it is EXACTLY the same. I am sure that some powders have changed just a little along with primers. The old deal about using modern data appears to be a moot point-at least with Alliant. The 20 year old data was for Hercules powder! Comments appreciated.

If there is no reason to retest the data they don't. If a different bullet is released and they want to provide data for it they will retest, otherwise they reprint.

No load data sourse has new data printed every time they release a new manual. They will test new cartridges and new powders but not the old stuff. There wouldn't be enough time in a decade to do that!