I' ve owned a .223 M-70 and a custom .22-250 M-70 and a .220 M70 heavy barrel.

The .223 is used more than 75% of the time on prairie dogs.....it' s a easier gun to shoot, it' s cheaper and personally, I can' t tell the difference out to 250 yards in any of them. When the shooting goes past 400 I use a .243 super rockchucker.....

In my book the .223 is the finest lettle varmint round I' ve ever owned.