Re: 223 suggested loads
With a powder that can be as unstable and variable as AA 2520 its hard to say. Being the 64 is a flat base, I'd bet the bearing surface is pretty similar to the 69 and with only 5 grains less weight-- try your normal load and see what happens would be my thoughts.
Varget doesn't meter bad and its pretty easy to get along with. I"ve dumped all my 300 yard line rapid fire ammo with a Dillon and varget and shot really tight groups that way. Mostly because if you are in a sweet spot with varget a few tenths one way or another just don't matter at short ranges like 300 and under.
Beware AA powders. Being surplus and bought from differing countries at times, they can change drastically from one lot to another and 2520 is pretty temp sensitive when I shot it years ago.
Good luck, Jeff
Get as close as you can, but utilize your skills as needed.