A grizzly bear was killed by a .22 caliber rifle in 1953. The bear, which was the largest on record at the time, was shot by Bella Twin, a small game hunter from Canada. She used a single shot from her .22 caliber rifle to kill the bear, which weighed over 1,100 pounds.
Here is the best account of Bella Twin and her shooting of the 1953 world record grizzly bear near the village of Slave Lake, Alberta.