That makes no sense to me either, but guns do not have sense so it might be the gun. The ejection disparity between the lead and copper rounds is obviously caused by something. Your experience is that the FTEs happen after firing a round and when racking the slide to eject. If it were only when firing, I would guess it was casing expansion but since it also occurs without firing that hypothesis fails.
That leads me to believe there are these possibilities.
1. The ejector malfunctions with certain ammo.
2. The casings on the ammo that fails have a tiny bit more diameter.
3. The chamber of your pistol is out of tolerance which could be residue or brass buildup, or it could be out of tolerance upon manufacture.
My recommendation is that you first call CCI and explain what you are experiencing to customer service and see it they have any idea about the cause. If they do not, then I think you have to call Walther to have the gun sent back for examination.
Finally, since the problem was not evident initially when you shot the gun it makes me think that either the chamber has some minuscule debris or the ejector is damaged.
Beyond what I have written I have no more thoughts about the cause. Good luck in getting the problem resolved.
Added: one more thought. It might be that the casing of the copper rounds expands when the bullet I’d pressed into place. Since the led is softer it would not likely do that. Just another possibility to question.
Also, when you clean the chamber remember that is is a greater diameter than the barrel. So a 22 wire brush is not going to clean it as well as possible. Clean the chamber from the chamber opening and be certain to put adjust pressure to assure good contact with the chamber walls.
I have ordered a 25 caliber brush and it should be getting delivered today so I will try and clean with that one. I have also seen videos for cleaning this gun that they use an air compressor....I did not do that...I wonder if that indeed needs to be done on this weapon.
I have emailed Walther and they sent back an email about the ammo to use and I was using one of the ones that they recommend.
I am wondering if polishing the feed would cure the problem.
How would the ejector get damaged from cleaning it?
Again, forgive me because I am very new to this.