I purchased a bolt and carrier assembly today at a local gun show. Upon arriving home, I attempted to fit it into my newly purchased upper. The carrier would not go all the way in. I then tried it in my older upper, it fit, but would not then come out easily. I really had to pull. No way would it have cycled reliably. I then compared the assembly to my original. They look the same, with the exception that the cut-out on the bottom of the new carrier is smaller, and there is no notch at the bottom of the cut-out. Any help would be greatly appreciated.

Thanks.

No way to tell for sure, without having the thing in front of me, but a couple of things you could check out.

See if you can figure out where it's rubbing by wear on the finish. It should be only touching at the rails on the top and bottom of each side, and to a lesser extent, at the sides of the gas key.  If this proves out, I'd try the carrier, by itself, and with the charging handle out of the rifle. If it goes in OK, then you know that the rubbing is eaither on the sides of the gas key, or in some way connected to the bolt/carrier fit.

Just keep trying different approaches until you can identify where the mismatch is.  My wild guess hunch is that either the bearing shoulders on the sides of the carrier were milled too large, or the gas key sides are too wide; but he only way to find out for sure is to have the thing in front of you.  Good luck with the search, and I sure hope the thing is correctable.[:D]

Shamayin,
Thanks for your timely response. After playin with  the carrier all day, I'm still unable to make it function. Hopefully, the vendor I purchased it from is still at the show tomorrow, and will be willing to make an exchange for one that will work. I'm going to bring my old carrier this time ( for comparison purposes!)

It sounds like you simply got a crappy carrier.  Unfortunate.  If it was really cheap, now you know why.

At $110 for a Supposed "black-tac" finish, I wouldn't call it cheap. Fortunately, I took it back today, explained the problem, and the seller was kind enough to exchange it for a chrome carrier that works.
I also managed to pick up a Springfield 1911 A1 Mil-spec for $390, so it was a pretty good day!