Thread: "Feather in my hat" 308win Featherweight load development

Originally Posted by grandpamac

Greetings @flock,
IMR4064 and Varget are two different powders and you should not use the data from one for the other. I have tested the two side by side and in limited loads found IMR4064 a little faster with the 165 grain and a lot faster with the 150 grain in the .308. The 45 grain load for IMR4064 appeared in the no 9 Speer Manual (1976) with a little less velocity due to a shorter barrel. The Hodgdon data for Varget is dated from about 1990 and their data for IMR4064 is much more recent. This is the best data we have currently. Differences in case capacity and projectile hardness need to be taken into account as well.
I see that Hodgdon needs over a grain more IMR4064 to get the same velocity with the 165 grain projectile which suggests to me that the IMI case they used is on the heavy side. The federal case they used certainly is. Handloading is chock full of variables which I guess is why some find it so fascinating.
Regards Grandpamac.

I used the current ADI powder equivalence charts, so interesting what you are saying.


Perhaps the chart is confusing showing 2 different IMR powders