Scratching my head: 7x57 load development

[FlyGuy]

I have sometimes gotten good 7x57 loads with IMR 4064, but USUALLY it all comes back around to 3031.

I've had excellent performance with 3031 using the lighter 7mm bullets, as well as 150gr bullets in .308.
Highly underrated powder IMHO.

 

[ZG47]

The original .220 Swift factory ammunition was loaded with IMR 3031 BUT the large rifle primer pockets had small rifle flash holes, in order to keep pressures down. You do what you have to, whilst waiting for the right product to enter full production.