There are many ways to go about removing the factory or other finish to get it to matte. This is what I've done before:
* Disassemble the cylinder
* Let it soak overnight in Hoppes/Break Free Powder Blast, this makes starting with a clean cylinder very, very easy.
* 1000 grit sandpaper, use until the finish is gone, anything finer than this you will begin to polish it, waste of time if you want matte.
* Wash it with water and soap, dry it thoroughly.
* Depending on what kind of matte you want will depend on what you use next. There are a couple of different kinds of 3M/Scotch brite pads that at this point will give you whatever kind of matte you'd like.
Or, you could have the cylinder blasted and you'll get a matte finish very quickly. This isn't free though and I personally don't like having any part blasted unless it has to be.