I recently participated in a thread, here...

 

viewtopic.php?f=22&t=4202

 

that tallked about a particular load of Blue Dot powder in the .44 mag with 240 gr. bullets. Tony357 pointed out that the current max load for that configuration is 13.7 grs. I stated that I used to use 16.5 grs. and that was within recommendations AT THE TIME IT WAS LOADED. (Tony your concern is appreciated, and I wouldn't load that today, but I literally put hundreds of rounds, with that load, down range.)

 

So after confirming that 16.5 grs (behind a 240 gr Speer JSP) was indeed tha load I used, I started to dig for old loading manuals. What I found was a terrific example of why only CURRENT loading data should be used.

 

Tony found a 1983 Hercules manual that stated 16.0 grs was the max load.

 

I found a 1978 Hercules manual that states 18.5 grs - that's 2.5 gr. difference in only 5 years. I went further and found two old Speer reloading manuals (yeah, yeah, I never throw anything away). A Speer #9 from 1974 that states a max of 15.5 grs. and a Speer #10 from 1979 (my reference for putting together the loads I used) that states a max of 17.2 grs. (I have these three sources saved as .pdf files - which the board does not accept for attachments. If anybody wants to see them just PM me with your e-mail address and I'll send them along.)

 

Chronologically:

1974 - 15.5 grs (Speer)

1978 - 18.5 grs. (Hercules)

1979 - 17.2 grs. (Speer)

1983 - 16.0 grs (Hercules)

2009 - 13.7 grs. (Unknown)

 

What's the difference? It could be changes in the powder formulation. There was a change in manufacturers from Hercules to Alliant that may have been a contributing factor. But more likely a difference in testing methods and equipment and our own litigious society. Clear up to Speer #8 the only methods Speer used for determing excessive pressure were: 1) Primer appearance; 2) Ease of extraction; 3) Case head expansion. After that period the use of copper crushers and piezo electric transducers were used. Today, we measure cartridge pressure in PSI (pounds per square inch) as opposed to the earlier measure of CUP (copper units of pressure). And, as stated, probably the largest factor: Lawyers and society's propensity to sue at the drop of a hat. I would bet that the data in Speer #9 was just copied from previous dada with no empirical testing. Speer #10 probably reflects data that was arrived at by their new testing methods. At the time, powder manufacturer's loads, which only stated a generic bullet weight, generally were hotter than the bullet manufacturer's, that were bullet specific.

 

Just found all this interesting. I'm sure that you can find parallels with other loads, but all of this just points up the fact: USE THE MOST CURRENT LOAD DATA AVAILABLE.

 

Adios,

 

Pizza Bob

Good info Bob.

That is an eye opener.. Also the fact that they came out with a service bullietien not to use blue dot in 41mag.. which the older books have the data!!!!

Well buy a new book more often not every 20 years.

i have been using the same loads of red dot for over 40 years in many calibers - some of the newer manuals show them as being over maximum - called alliant + speer - powders have not changed but product liability insurance premiums have - i still use the old loads - make double sure that you work up to max loads slowly + carefully check for any signs of excess pressure - make sure that the weapons you are using are in good condition -