Safe target distance?

[Riggs]

I have been looking around for a target that reacts when hit (movement or sound) and can be fired at with a rifle at close range. So far the closest thing I have come up with is this

Amazon.com : Do-All Outdoors Impact Seal Self Healing Big Gong Show Reactive Target : Hunting Targets And Accessories : Sports & Outdoors

My theory is that because the round is not breaking up on the target but instead passing through it, I can engage it much closer than with a steel target.

Has anyone had any experience with these, or any idea how close these targets can be safely engaged with rifle rounds? (5.56x45, 7.62x39)

Thanks