If it is loose with it closed you need to shim the barrel at the underlug to tighten it up.
It's not really a big deal when it's opened, it's more of an annoyance. Does the gun have wood or synthetic stocks on it?
Check out the FAQ's link in the H&R centerfire section. There is a section on barrel fitting for the novice. Some very good info. that will help you.
Spanky