Had to replce my gas tube the other day and I'm having trouble getting the new one in. It goes right through the upper and delta assembly but seems to be stuck 1/2 in the sight tower. I cant wiggle it in or out now and it's not seated far enough forward yet. I don't want to damage it by pounding it home. Any advice or suggestions? I just happened to think, is it possible I have this in upside down? Is the gas hole supposed to be pointing up or down? I believe I have it pointing up.

The gas hole is supposed to be pointing down towards the barrel.

You can always use some tape as padding and carefully use some pliers to twist and position the gas tube.  If you don't mind spending $30, this [url=http://www.bushmaster.com/shopping/gunsmith/mbc-01.asp]gas tube wrench[/url] works great.

Man that little bastard is really stuck!!! I think I'm goin to have to cut it to get it out. Donno what the problem is but no matter how I try, cant get a good grip on it.

If you're going to replace the gas tube, the easiest way to get it out is take some Vise-Grips and clamp down hard on the gas tube (yes, totally crushing it) near the front sight base.  Then you can whack the Vise-Grips with a hammer while twisting and the gas tube will come right out.

Since you now have a thrashed gas tube, cut out a straight section 2"-3" long to use as a barrel nut alignment tool.

for your next gas tube installation you may want to take a drill bit (7/64?) and hand turn in in the sight tower hole to clean all the crud out.  Even on a new barrel you can have a lot of crap in there, on one thats seen a few rounds you can have carbon.

Before you go crushing your present tube you might want to use a piece of rubber between those visegrips and your tube to get a grip and try tapping on your grips to work the tube out.  If you have your tube in upside down its probably wedged in there.