1st day of vacation and I was getting ready to go to the range this morning when a severe thunderstorm changed my plans. Well, it gave me the time to try contacting someone at ebay by phone (quite a trip just finding the number). I should have known better, I found myself in a maze of recorded messages, and just plain BS, so I gave up. Instead I found a section in customer support, where you can report a member and/or items to an ebay agent, so I sent a detailed email listing the three brass pipe bombs this guy currently has listed, and the 14 past sales that include both steel and brass pipe bombs. I didn't mince any words in describing what I thought about this seller's product, or the hazards that buyers could be facing if they try to fire them.
My suggestion would be to wait on taking any further action for a few days, just to see what kind of response they give.