Only the last round, even while cycling them through by hand.  When firing the case lodges between the barrel and slide, smashing the crap out of the shell and locking up the gun.  When cycling them through by hand the round just stays in the port but pulls out from the chamber.

Could a recoil buffer be causing this?  This is a used gun and it has one.  Also i just bought a full length guide rod, could that help out?

Your extractor doesn't have enough tension/isn't holding the case...

Take the slide off the frame

Turn slide upside down

Take a dummy cartridge, manually slide it UNDER the extractor, against the breech face

Turn slide back upright

The cartridge should not fall out of the slide. If it does, you need to either re-adjust the extractor tension (there are tools for it), or get a new extractor and hope it's within spec (Wilson Combat bullet-proof extractors are what I personally recommend)

(If you're wondering WTF, basically the cartridge is slid up under the extractor when the slide moves forward, and the extractor holds onto the case for the entire time...its not like most other handgun's extractors who's sole purpose is to pry it from the chamber. The extractor on a 1911 actually grips the thing and holds onto it until the ejector punches it out. If the extractor doesn't hold onto it the entire way the ejector can't punch it out, leading to the jam you have on the last round. The reason it doesn't happen on the first 6 rounds is because the bullet in the magazine beneath it props up the ejecting shell, keeping it in the extractor. Without that bullet in the magazine, the spent shell drops a little too far, the extractor can't keep a grip on it, the ejector punches it in the wrong place, and viola..jam.)

tag

Quoted: (If you're wondering WTF, basically the cartridge is slid up under the extractor when the slide moves forward, and the extractor holds onto the case for the entire time...its not like most other handgun's extractors who's sole purpose is to pry it from the chamber. The extractor on a 1911 actually grips the thing and holds onto it until the ejector punches it out. If the extractor doesn't hold onto it the entire way the ejector can't punch it out, leading to the jam you have on the last round. The reason it doesn't happen on the first 6 rounds is because the bullet in the magazine beneath it props up the ejecting shell, keeping it in the extractor. Without that bullet in the magazine, the spent shell drops a little too far, the extractor can't keep a grip on it, the ejector punches it in the wrong place, and viola..jam.)

I learned something today. Thanks for the tip.

If all expended rounds but the last are ejecting, try switching out your mag. Or does this occur with other mags as well?

ETA- Try a different mag before moving on to the extractor.

The reason I came up with this explanation, BTW, is because the exact same thing happened to me, and continues to happen on one of my 1911's (which I'll fix when I get around to it...already fixed one, that has me happy for now)

If I insert a dummy round into a magazine, yank back the slide and let the dummy round seat, eject the mag, and sloooowly pull back the slide...the round should NOT fall out. It should droop a little bit, but not fall out. The round should make contact with the ejector and move diagonally out.

I bet if you do the same thing with your 1911, Zip, the round will fall totally out. (Sounds like it in your first post anyway, but this is a good litmus test)

The two basic problems would be either a) the extractor hook is too long (possible) or b) not enough extractor tension (also possible, and a lot easier to fix)

As suggested, try another magazine, but the symptoms don't fit a magazine problem, IMO.

Always remember...modify/fix/change the cheap parts first

The ejector is way loose, thanks.

So how can i fix it?

You can buy a bending jig from Brownells to bend it back to what you want, or you can bend it yourself...or you can just buy a pre-tensioned extractor like the Wilson Combat one, and just swap the bugger out.

I bought the extractor tensioning tool myself, because I had an out of spec slide that the pre-tensioned extractors didnt work so well in...

But, if you want to save the muss and fuss and spending an hour or two of bending and checking and re-bending (or un-bending), just get the new extractor and odds are it'll work just fine.

Either way, it'll be like $30 or so.

Not a huge deal.