One of the issues I had with my Glock 20C when it was new was that the factory installed the wrong spring loaded bearing for the loaded chamber indicator (LCI) extractor. The pistol worked fine for about 200 rounds, but then started to fail to feed and eject. I replaced the extractor with the older non-LCI version and the correct spring loaded bearing, and that solved all issues. Might be worth looking at after you try going back to the factory barrel.  Here's a link that shows the difference between the two. The front of the LCI bearing is longer than the older version.

http://www.lonewolfdist.com/Products.aspx?CAT=175

I guess I am lucky, I have a 29sf with a 4.6 ported from lone wolf and a stainless guide rod with 22# springs and any combination of stock and after market springs and barrels works with any ammo . I am no gun expert but the lone wolf barrel passes the plunk test with all ammo. It is the loosest feeling pistol I own but it is minute of coke can and a riot to shoot. I am a recoil where and with a magazine full of underwoods I just love the feeling of power... I find myself looking where I to put the quarter in for the next ride.
Russ

So I went back to the original barrel with the aftermarket recoil spring and shot around 125 rounds with all my mags and had only 1 FTF with 200 grain Underwood hardcast (looked like the round hardly moved up, totally horizontal.  Racking chambered it.).  Shot my handloads (went with a shorter O.A.L.), 180gr Underwood TMJ, and a box of Underwood 200 grain hardcast.

I need to measure the brass to see if there were any smiles.

So it does look like the aftermarket KKM barrel was causing all the FTF and FTF problems.

Question now, with the 1 FTF, is if I feel comfortable enough carrying it into grizzly land in a couple weeks.

Keep putting rounds through it and see if its a big problem or not.