I think that the 12 loads with IMR4320 , 50.5 and the 165 grain bullet would have fine.
Its the others with the varying powder charge of unknown powder that really worry me...
Andy
As someone who is still a newbie reloader, I'm curious - how did you know it was 4320? Was something on the box marked, or was the look of the powder that obvious? I know there are variations in grain size, shape, etc. in different powders, but with so many on the market, can you tell just by looking?