I'm actually excited I just broke my ejector on my MP5K PDW Clone...
Since I bought this CA89 back when I lived in Colorado in 2012/2013, I have had issues with double feeds. On the way to the shooting range a few days ago I got a hold of Dakota Tactical to see if they could take a look at it. They refereed me elsewhere, but suggested that I clean and inspect the flutes using a bore scope. I cleaned and inspected them at the range, but they actually looked remarkably clean. I shot five rounds before I had a double feed. I dropped the mag and of course a spent casing and live bullet fell out. I charged it again shot three rounds and had a another double feed. I cleared the malfunction and this time I noticed the top of my ejector fell out with a casing and the live round. I though to myself "Great, another part I have to replace." It didn't hit me until I was emailing RDTS for help, that the ejector was perhaps the problem all these years; it's one of the only parts I never replaced. For some reason I had kept thinking my rifle was failing to extract the rounds from the barrel causing the double feeds which is an astronomical oversight. I feel retarded because I replaced the entire bolt and several other springs at a cost well over $300, when the whole time the rifle was failing to eject the spent casings (see attached pictures). So if this 3rd gen ejector from HKparts that I just ordered for $47 works, this rifle will be running like a champ, or at least running like a shitty CA89 should be running.