I've got an M16A1 upper from CDNN and am trying to replace the ejection port door spring but I need to break the barrel down.

The gas tube is stuck!!!  Roll pin out and that SOB will not move at all!

Help, any ideas would be appreciated.

I have tried the pliers/hammer routine and am afraid if I clamp down any harder I will crush the tube.

FH

keep the bbl. on, remove the tiny c-clip that is on the rod and slide it out the other end.



the tube could be removed if you work it back and forth to break it loose, if not use some pliers with a rag around it to work it loose. if none of that works soaking it in solvent might work or a new gas tube.

You've lost me...sorry to be a newbie on this.  What c-clamp are you talking about?

the tube is free moving in the upper just locked solid in the FSB.

I may have to try the solvent route.

Thanks, FH

 There is a very tiny C-clip on the front of the hinge rod.  If you remove this, the rod will slide toward the back of the receiver.  This way you will not need to remove the barrel.
 
 If you need to get the gas tube out, first use a good penetrating oil, such as Kroil.  Then turn your upper upside down and clamp the gas tude in your vice.  Be carefull not to crush the gas tube.  This will allow you to turn the gas tube in the FSB and slide it out while working the upper back and forth.

Weazer

The C clip is usually just in front of the dust cover front hinge hole on the reciever.  Put a magnet next to the pin as you remove the C clip, it will fly into oblivion if you give the slightest chance.

Looks like there is a bit of confusion here.
First the gas tube or the barrel does NOT need to be removed to remove the dust cover plate and hinge pin.  there is  a C clip at the muzzle end of the hinge pin that is removed and the dust cover hinge pin gently slides towards the buttstock for removal.
That said.
I'll assume you have removed the roll pin out of the gas tube in the front sight base?
using safe pressure from pliers or other clamp type grasp the gas tube on the angle bend just infront of the upper receiver and ensure that it will turn, if its free it should slide back into the upper receiver enough to clear the front sight base and then pull muzzle wards to remove.
Hope this helps

Sgt Bingham

Thanks for the clarification...I figured out that we were talking about the c-clamp on the hinge pin instead of some unknown new thing in the FSB about three posts ago (as I was out shooting the PITA AR!  The tube is still stuck but I will try some of the ideas to get it out.

I have now changed the spring so many thanks on that (eyesight getting worse for close up stuff...did not see that c-clamp!)

Thanks folks, FH

Take your handguard off, turn your AR upside down, clamp the gas tube in a vise, don't worry about hurting it except in extreme circumstances, and pull the the entire rifle to the front or lightly tap it until the gas tube comes loose.

Quoted: Thanks for the clarification...I figured out that we were talking about the c-clamp on the hinge pin instead of some unknown new thing in the FSB about three posts ago (as I was out shooting the PITA AR!  The tube is still stuck but I will try some of the ideas to get it out. I have now changed the spring so many thanks on that (eyesight getting worse for close up stuff...did not see that c-clamp!) Thanks folks, FH

well if you cant tell the difference in a c-clip then it's the slight bulge on the straight rod.

Quoted: Take your handguard off, turn your AR upside down, clamp the gas tube in a vise, don't worry about hurting it except in extreme circumstances, and pull the the entire rifle to the front or lightly tap it until the gas tube comes loose.

great idea right there, i would have never thought of it.