Gunworld has a pretty short list of calibers they will let you shoot in there. When they told me I couldn't shoot my AK because someone had snuck some steel core rounds in there, I asked if they would consider selling me some rounds that they approve. They got pretty rude with me and so I don't grace thier door anymore.
The steel core rounds are a problem with steel targets and people shooting the .22 and pistol targets with rifles! the steel targets are expensive. not saying they should get rude but up keep is a lot of work and cost. just my 2 cents.