I bought my 220 in the early 80’s. It’s an old tang safety Ruger from the mid 70’s. Back then, some gun writer said that the gold standard load for the 220 was 38.5 gr of IMR 4064 behind a 55 gr bullet. I worked up to that load, found he was right, and that’s the same load I use today.
Just going to throw this out there for info. According to Phil Sharpes 1938 book Winchester produced 3 factory loads.
45 grain bullet, 41 grains 4064 for 4250 FPS
48 grain bullet, 39 grains 3031 for 4140
56 grain bullet, 34.5 grains 3031 for 3497
