If you're just going to shoot at moths and bees and such things, I would just load any pistol shot load with something like salt or the old walnut media from a case polisher.
Cornmeal or grits as mentioned above sounds like it could work.
10 or 15 ft it'll probably do in the little buzzers and no issue beyond that doing any damage .
For snakes and such,,I don't think I'd trust even the commercial stuff for that.
Since you are taking a step into the world of 'loading' .22RF, and wondering what powder and how much to use,,I'd think twice about guessing about what powder and especially with a lead (shot) load.
Tightgroup powder for use in reloading .22LR Shot?,,I don't know.
There's a (re)loading tool sold to reload fired .22LR cases.
That includes instructions and a powder chart that has 700X, Unique and some other smokeless powders on it. They also have Pyrodex listed. Their reloading is for 2 different weights of cast lead bullets,,no shot loads that I remember.
Most all .22LR commercial ammo has a powder charge or +/- 1gr.
So you're not allowed much room to roam in reloading.
That's about the only 'data' I can recall for reloading .22LR. If you call one of the ammo mfg'rs, they will just tell you it's a special proprietary powder made especially for their rimfires. Or they won't even tell you that.
The OP mentioned perhaps using just a primed LR case alone,,no powder.
Try it I guess. No harm in that.
Pressures can go up very quickly in any cartridge when using the wrong powder and bullet weight combinations. The little .22LR already runs around 24K in regular ammo if I'm not mistaken.
Not something to guess at.
The idea mentioned of using clipped up pieces of copper wire for a shot load would be a light weight alternative from lead but I'd be suspect of some of the pieces jamming in the bore trying to make it down the small dia barrel on any given shot.
At the smallest, the pieces would be around #7.5 shot size and likely larger. Not a lot can be stuffed into a .22LR.
Just some thoughts.
