If you are having a FTE, the the extractors need to be tuned, as well if the cartridge won't feed out of the mag lips and hanging on the breechface, then that could be either a mag lip problem or an aggressive extractor (or a couple of other things.).
Ummm - can you post details? As well - get the plunger tube installed (you have the spring set/keeper,plungers for it - right?), so it will feed or not without interference (ie "falling apart"
)
On that note - I'll look for a tube assy for you tonite or tomorrow AM, OK?
Best to you!