Having multiple manuals is never a bad thing. I personally like Hornady, Speer, Lyman, and Nosler.
In regards to the H vs IMR. They both make a 4350 but they ARE NOT, I repeat ARE NOT the same powder. IMR 4350 is made in the General Dynamics plant in Canada. H 4350 is made in Australia by ADI. The charge weights might be similar, but rarely the same, and if they are the same it's purely by coincidence. Those 2 powders are not interchangeable in regards to the charge weights for any given cartridge. The reason is due to different pressures generated. This explains why you'll see differences in various data and manuals.
