Original A.T. Cross Century ballpoint refills for twist pens cost about 7$ to 10$ but they last and fit well. China started to produce some Cross ballpoint compatible refills and pens and to my big surprise they even managed
to sell them via my local Staples store. The chinese refills don't actually fit into an original cross pen and they cost only a few cents when you buy them in china via aliexpress. At
the local Staples store they are now sold for the same price as original A.T. Cross ballpoint refills. As a customer you can't identify the difference while you are in the store. There is only a very small difference between the chinese version and the genuine cross version.
Here is a photo. The refill on the left is the chinese one and the two on the right are genuine cross refills.
Chinese imitation cross pens do not have a hub that holds and guides the ballpoint refill. Real cross pens look on the inside as shown in the drawing below. There is a hub that holds the refill in place and minimizes the wiggle of the refill.
The net result is that chinese refills (even when sold for a high price a Staples) don't fit into a genuine cross pen. The chinese refill emerges only a little bit from the pen and you end up hitting the paper with the metal of the pen especially when you hold it at an angle. The first photo shows a genuine cross pen with a chinese refill installed and the second photo shows the identical pen with a genuine cross refill:
Is it possible to fix this and make a chinese refill fit? We need to make the thinner section at the tip of the refill a little longer. If you look carefully at the chinese refill then you notice that the tip section is pushed into the metal pipe that holds the main ink reservoir but there is a bit of metal before the pipe starts and we could file that off.
So here is what I did: I removed the plastic cap at the end of the chinese refill and I installed the refill into an electric drill. I got a second person to run the electric drill at medium speed. I put on a leather glove to hold and stabilize the refill while it was turning and then I took a small file (I used a round file) and pressed the file against the metal that needed to be removed while the refill turned. Essentially I was using an electric drill as a lathe.
The result is shown here. The refill in the front is an unmodified chinese refill and the one in the back has been filed down with my "electric drill lathe":