I looked in the barrel and chamber after the Test #1 firing of 5 rounds. Could not see any trash or residue at that time.
As an indicator of the two - See the following picture. The Test #2 brass (and fail to fire) are on the left. The right is from the Test #1. Notice how dirty the Brass on the left is; chamber is collecting trash too from the 5 rounds.
I'll be cleaning the rifle in a little bit.
Click on picture to enlarge.