Make sure that the suppressor you're getting fits under the rail.
To be classified as a DMR or sniper rifle (and thereby fall in the 450fps limit) it must be limited to semi-auto only.
If you put a longer inner barrel on your M4, you're going to need to change to an un-ported cylinder as well. If you don't know what I'm talking about, its best to get a gun tech to do this for you.
Last edited by Wrath144; December 21st, 2010 at 01:34..