I use Bowling Pins all the time. I have one alley that will give them to me. The range I go to also sells them for $1 each. The plastic shell holds most bullets inside the pin so it gets larger. .223 rounds are a bit hard on bowling pins and will tear them apart. I try to stick with handguns.
You can also take a set of Saw Horses and take a 5 -6 foot 2x4 and then hang the bowling pins so the swing when you shoot them. I have tried screwing in eye bolts in the top and then using a small chain it works. You can also just tie some string around the neck. Bowling Pins are one of my favorite targets.