I'm not familiar with what you are calling a Ground Squirrel, in your part of the country. Here in the Midwest, they are small and perhaps a stretch at 70yds. I have both the Holo's and RedDots on my 10/22 and they work great for the Fox and Grey Squirrels we encounter. ...
The last time I was in California I saw Squirrels that were digging burrows on a hill side. They were rather large and asked a local, what they were called. He said; Ground Squirrels. Okay !!
Be Safe !!!