Chris, if you wish to discuss the M-4, that's great, but there are a couple things you need to do before opening up a new thread.
First, do a search for existing threads on the topic. There are several threads on assault rifles that have a lot of information on the M-4, along with comparisons with other assault rifles in the same class. Take a little time to read up on what has already been discussed. Chances are, the information you are looking for has already been posted. If not, you can post your questions in the existing thread.
Second, you are expected to read the descriptions of each forum, and post in the appropriate place. Infantry weapons are discussed under Land Forces, not Defence Tech. If you open a thread in the wrong forum, it may locked or deleted without warning.
When you do open a new thread, you need to give a opening to the discussion. So please take the time to acquaint yourself with the basics of the topic before you post, and then give us some idea of what you are trying to learn, or where you want to go with the discussion.
When you say "tell me about the M-4", you are likely to get a response like "it's a gun". Crappy questions invite crappy answers.
If you have any more questions, go ahead and PM myself or Webs, or one of the other Mods, and we will try to answer them for you.