I own a recently born Gen 3 (TTL*** 8/2012). I quickly noticed the erratic ejection with target ammo. In particular, Federal 115 gr fmj would eject BTF or top of head 10-20%. It has never had a FTE and no stove pipes in 1000+ rds. So in reading all the discussion and debate about potential solutions, I examined the pieces/parts that have been in question. My extractor is a non-dip MIM, so I decided since this type seems to have less reported issues, I would start by replacing the ejector. It was the 336. I ordered a Gen 4 trigger block from Lone Wolf which they stated had the 30274 ejector and traded out the ejector. (The Gen 4 trigger block is not compatible with the Gen 3) This was a total of $12 for part with shipping. I am happy to report that I shot 100 rds with it today using the same ammo as before and had the most consistent and proper ejection of shells to date with no BTF.
Obviously, plenty more rounds will be necessary to deem it as completely cured, but a good start!
I realize that many people have had limited success with replacing/trying different things, but this was a fairly inexpensive one that may be worthy of being the first thing to try.
Good luck to all Glock owners in their pursuit of Glock Perfection!