I have a DPMS ar-15 with the 6 inch supressor/brake on it.  I want to attatch a different supressor and am having one heck of a time getting this one removed.  I have head that it is meant to be permanently atatched, but nothing is permanent and there is a little play from the barrell so I know it's not welded on.  Do you guys have any insight as to how I can remove it.  

1.  On most of those 5.5" flash hider/
commando" barrels - they were placed on 10.5 or 11.5" barrels.... so understand your rifle will be an illegal SBR once you remove it.  (Unless this is on a machinegun)  Are you planning on registering your weapon as a SBR first?

2.  You shoul contact DPMS and inqure about the method of their "permanent" attachment.  Typically, these are blind pinned and welded over, then parked, welded, or high temp solder used.  The method of attachment will determine the method of removal.