Ted;
My experience in the squirrel woods somewhat mirrors yours. However, in my experience, the Dividing line is not so much total noise as it is the Sonic Crack.
I have many times been beneath a tree which the Squirrels were working with several under it, pick one off using those standard vel LR's & the rest not even quit cutting. I did a lot of my hunting early while the leaves were still on, so I would then just start trying to get enough view of another to line up on. If they did stop, as you say would be only a very few minutes until they were back at work, if you didn't otherwise disturb them. Have even had the same results when I was using a shotgun as long as it was one of the lower velocity loads.
Normally one shot from a Hi-Speed .22 LR with its Sonic Crack would Clear the Tree in short order. As long as I stayed with the lower velocity LR's I had no more concern over the noise level than with shorts. In this regard, a pistol would be louder, but slower so one would not have the Crack.
Stan;
I built a .32 cal long rifle particularly to squirrel hunt with. It was plenty accurate with round balls for the job but could not be loaded for the 2nd shot without cleaning when using light loads. There would be a spot where apparently the powder was all burned up that would leave a big amount of fouling. By incrementally increasing the load that spot moved accordingly toward the muzzle. It didn't move out of the muzzle until somewhere around 50 grains of 3F. Velocity was so high it simply devastated a squirrel.
I then put a .45 caliber barrel on it, still with a round ball twist, & amazingly I could load it down to 20 grains & shoot it all day. It was much less destructive on a squirrel than was the .32 with the Hot Loads. It was accurate enough you could simply behead a squirrel & waste not an iota of meat unless one is a brain & tongue eater. It was also subsonic & would not clear a tree either, even though much louder than a .22 of any sort. The heavy loaded .32 had a Sharp Crack to it.
