This pack contains skin replacements for both M4A1 and Famas. You can choose one and don't have to replace both. When using "Lily Bowen's Silenced Assault Carbine", make sure you use the correct sound file or you will end up having no silencer with silenced firing sound and vice versa.
Removing the black outlines won't make any differences. It's about how do you color the details and such. I can hardly find any lightnings / proper shadings in there. Details are fine, but not the one I mentioned earlier..
All the times I spent spriting somewhere else, I can't help to think that all of your weapons looks flat to me. The details need some more darker colors so that it will show up more.
I made the skins look similar with only a few changes because the gun would look different and be different in game. So for example: Extended mags would replace M4A1 because it has a bigger chamber.