My Gen3 G27, NRR prefix ejected fine at first but at 200 rounds I and a relative noticed some spent casings going over my head. I thought nothing of it and just kept shooting until 300 when some were going straight up in the air then landing back on my arms or on the top of the slide. Then I inspected the spent casings and saw a big dent/scrape at the case mouths with corresponding brass dust and smearing on the lower ejection port of the slide. I tried different ammo, same results. I had kept some of the first spent casings fired through this gun and they did not have the dent/scrape. Once the ejection problem started, 98% of the spent casings had the dent/scrape at the case mouth and about 10% were either ejecting over my head or straight up in the air. The dents/scrapes at the case mouths are similar to my Paint drawing below:
My extractor was of the "MIM" flat top type and the claw became jagged, this must be really soft metal. I tried the extractor from my G23 which ejects fine(it's an older investment cast extractor), it eliminated most of the straight up ejections but not all, but it did not change the percentage of erratic ejections or casings with the dent/scrape. I tried a non-LCI 15 degree .40 extractor(also investment cast) with non-LCI SLB that I found in a local gun store, I had the same results as with my G23 extractor. I also tried a LWD .40 extractor which I later discovered to be a 9mm extractor, it of course made ejections much worse with some casings actually going downrange and to the left or over my left shoulder. I tried a new RSA, a new trigger housing w/1882 ejector, and they made no difference. I tried an HRED .40 EDP assembly, it made ejections more forceful but did not change how erratic they were.
I was considering reprofiling the 1882 ejector as JBarbaresi had successfully done to his 336 ejector with a rearward and slightly offset to the right angle to the face of the ejector when Glock released the new "Gen4" ejectors. I decided to wait and I'm glad I did. Before the new ejectors were available in the newest Gen4 trigger housings, another member of this forum tried a .40 28926 ejector in one of his guns and it made no difference, so he sent it to me. I removed the 1882 ejector from my Gen3 trigger housing and inserted the 28926 ejector. It fixed the ejection problem, I also used the non-LCI extractor as a replacement because I didn't trust the "MIM" one. All casings now eject to the right between 3 o'clock and 5 o'clock and there are no more dents/scrapes at the case mouths. There is a tiny scrape midway down the length of 50% of the casings as shown below in my Paint drawing:
I forgot to mention, with the 1882 ejector I compared some spent casings from my G23 and G27. The ejector marking on the 23 casings was low and left as it should be, but they were middle to high left on the 27 casings and sometimes the ejector even gouged the edge of the primer. The 28926 ejector leaves no marking that I can detect. I also noticed some pretty severe scoring of the muzzle end of the EDP, it seems to be rubbing against the opening in the slide pretty hard. My G23 EDP does not have such severe wear. I did not notice that wear on the HRED EDP but I only shot 100 rounds with it.