re: My new Glock 19 jams a bunch

It's pretty hard to jam a Glock due to lubrication -- unless maybe you get too much in the chamber (shouldn't have any in there, nor any in the bore).

It's easy to get failures-to-fire if you get oil & the resulting goop in the striker channel. But the OP didn't mention FTF's.

I doubt if it's the position of the guide rod (first step, second step, etc). It should be placed into the "step" that's closest to the barrel -- but it may well jump to the other step while firing. No big deal.

Over-oiling any pistol, including Glocks, isn't good. So is under-lubing one. But that's unlikely to cause a firing//extraction//ejection issue.

I'm still not clear on exactly what's happening. I think the OP said "failure-to eject" --- but it sounds like the empty casing is not being extracted from the chamber (failure-to-extract), and then he's getting a double-feed ???

p.s. I'll still be glad to meet the OP at Precision. If we can't resolve the issue, I give him $75 for that POS.