Mike, I have been shooting all three Cowboy Silhouette disciplines for the last six years and I can tell you that in my opinion the first three targets do not represent much trouble to a .22 Rimfire if the stands are built properly and the targets are not set forward. Two of the local ranges where I shoot in CA. tend to use heavy targets on PC because some of the shooters use heavier than necessary loads in their .357s and 44 Mag rifles. I have many times shot those heavier than normal PC targets with a .22 using Lapua ScoreMax ammo (48gr bullets) without loosing more than one or two targets as long as I paid attention to how they were set before I shot.
More than once we have stopped shooters from using their hot loads because they were causing damage to the targets so encourage the participants to load for accuracy and not to use the heaviest recommended loads for the caliber they are using. .22 Magnumss do quite well in PC and because of their flat shooting and low recoil 20-25 and 32-20 are the ideal calibers, the .357 being probably the most popular caliber used because quite a few shooters use the same rifle with heavier loads for the Long Range match.
My suggestion to you is to make the first three targets as heavy as allowed for PC and then make two sets of Ram targets (.22 and PC) because the SB Rams are too heavy for .22s Standard Velocity ammo and are regularly rung if the wind if blowing from behind them, I know quite a few people that shoot SB with High Velocity ammo, the targets are huge compared to SB 1/5 size targets and you can get away with shooting ammo that does not give you under a minute of angle accuracy.
If you can afford the metal make also two sets of pigs. Chickens and turkeys will not give you much trouble with .22s even if they are on the heavy side but the Rams and some times the pigs will. I hope this helps you make a decision.
