I found a way to do the ricochet 100% of the time: There's a pipe that swings the 25 yard targets out of the way, it has a female coupler joining 2 pipes about 3" dia about 10-12 yards away at our outdoor range. If I shoot a .22 LR at it from about 30 degrees off to one side at the front top edge of the coupler, it's happens every time! Why? the round is deformed for sure, but also spinning due to the rifling and likely tumbling too. The spin of any round even with a 1 in 12 twist has a lot of energy that should not be ignored. The more a round distorts and the faster twist also helps. Very unlikely you'll get a ricochet sound off a tree, you need something harder.