Bristoe,
I did essentially the same thing with #4 buckshot when experimenting with the .22 Hornet, though I squeezed them through a Lee .224 sizer. One grain of Red Dot got around 900 fps, but accuracy was only good enough for 25-yard shooting, and even then the shot needed to be sorted for uniformity before being sized.
The accuracy of the buckshot load isn't nearly as good as with typical bullets, but it's decent out to 50 yards if you keep the velocity low,...and keeping the velocity low is necessary if you plan on eating things you shoot with them. For whatever reason, a .322" buckshot exhibits a surprising amount of disruption when fired from the little Martini at about 1900 fps.
At about 30 yards they'll explode a grapefruit. A couple of them virtually disappeared. I'd guess that a squirrel hit anywhere except the head would leave little for the cookpot after being hit by one.
