Lube?

Lube in the chamber or sizing lube left on the brass is not nice for your gun.

You shouldn't have oil in the barrel for that matter. It can create too much pressure. If you use excessive oil after cleaning, run a couple dry patches down the bore before you shoot it.

I have to ask about the range rules issue. How exactly is performing a safe and properly executed clearing drill (mortar - up and downrange) more unsafe than walking around with a hot round?