From around 1970 for the next 40+ years until I became physically unable to hunt anymore my Go-To gun was a 12 gauge with 26" barrels bored .012" right & 024" left. By the simple act of changing loads, I successfully took quail, woodcock, rabbit, squirrel (occasionally) duck & a few turkeys. maybe a few others, but can't really recall. This proved to be a most versatile combination for me.
Squirrels I normally hunted with a .22LR standard velocity but had a place I sometimes hunted where rifles were off-limits so the shotgun had to be used. This place had a better population of Fox Squirrels than my normal grounds.