"...No. 9 is an excellent choice for traditional magnum revolver cartridges... it has become one of my favorite powders for .357, .41 and .44 Magnums. It offers low muzzle flash and is clean burning. It does not require a magnum primer for ignition. (Note that ...AA-9 do not require a magnum primer, and neither are they suggested, to obtain correct ignition... If a magnum primer is used, the maximum charges should be reduced..."
Hornady recommends Small Pistol Magnum Primers for .357 Mag. and Large Pistol Primers for .44 Mag. in their reloading manuals. This is good to know, especially since magnum primers can somethings be difficult to locate.
A RESPONSE FROM RAMSHOT (ACCURATE)
Bob, Below is the reply to your question from our lab...
The loads can actually be used as is for all primers with only one exception, namely the CCI350 for which they should reduce the loads by 10%.
A RESPONSE FROM HORNADY
Bob, I would say that we do agree with that statement. We did not use magnum primers in our AA #9 loads in 41 Mag or 44 Mag. However, we did use them when assembling loads for the 357 Mag. Thank you!