Can't get AR-15 gas tube out of front sight / gas block

[energizzzer]

As the title states, I can't get the gas tube out of the front gas block....and yes, I have knocked out the roll pin.

I read somewhere that you aren't supposed to twist the gas tube out? Rather than damage something, I thought I'd ask here for advice.

Also, is it necessary at reassembly to use a new gas block roll pin?

Thanks

[TGO David]

Heat the front sight base / gas block area with a propane torch for a few seconds and then gently smack it forward toward the muzzle using a block of wood and a hammer. Baby steps; no big home-run swings with the hammer. Just firm taps.

Use the heat sparingly. It's not going to hurt the barrel or the gas block, but if you leave the torch just sitting on it too long you're going to risk of discoloring the black oxide finish.

You are using some sort of armorer's block to secure the upper receiver group into a vice, right?

[gunrunner32]

The only time you would really need to replace the gas tube roll pin would be if you damaged it in the removal process. I've never really had a problem removing one, but they can get a little sticky at times and as David said use heat sparingly. Keep at it if anything gas tubes are cheap. If you don't mind me asking what is the purpose of removing it?

[energizzzer]

Thanks guys. I'll try the torch.

Yes I'm using a bench block.

Removing gas tube from front sight base to replace with a low profile gas block. A necessary step to install my 10" LaRue handguard.

[TNRobocop]

It seems that David gave the procedure for removing the front sight base assembly from the barrel, rather than just the gas tube.

I have only this bit of advice. Do not try to remove the gas tube. Just replace it since it is cheap and will be a PITA and a source of never ending frustration to try to remove a carbon encrusted, dissimilar metal bonded, filthy gas tube without causing damage.

The original assembly w/ tube will be useful for use on a future build or you can sell it.

[Leadslinger]

If you have a bench vise, clamp the gas tube in the vise. Gently stike the back end of the upper receiver with a rubber mallet or like David stated with a block of wood and hammer. This worked for me. I had the same problem about a month ago.