GEORGE WALLACE says: There are two low power .22 Rimfire cartridges available, if you can find them.
Both RWS and CCCCI offer either BBBB Cap (which appeared in 1845 and originally used a .22 calibre round ball for indoor target shooting) or CBCB Cap format, and in various lengths to suit the chamber of any .22 rifle.
The one I have used is the CCCCI .22 CBCB Long, which will feed from the magazine of a .22 long rifle. It fires a 29 grain bullet at about 700 feet per second and produces 36 ft/lbs of muzzle energy. In power, therefore, it is similar to a very powerful air rifle.
If you can find some (and if your rifle will shoot them accurately) you may find them useful out to 40 or 50 yards.
However, be aware they have just as much potential to ricochet as the full-power round and will penetrate more than an inch of pine board at close range. They are definitely not toys.
Got a question? Contact: firstname.lastname@example.org or Sporting Gun, PO Box 157, Stamford, Lincolnshire PE9 9FU