Got this email today:
What you are seeing is the remnants of the factory proof charge. The rifles are proof tested and the brass end is supposed to be removed before shipping. I am very sorry that you received a rifle with the brass end still in it. It is spent and does not present any safety or function risk. Your rifle is good to use and should not have an issue.
If you would like to provide your address, I would be happy to send you some free accessories to make up for the dilemma.