I made a simple tool at zero cost to remove stuck gas tubes without crushing or scratching them.
1. Spray with Kroil, WD-40, Remington Wonder Lube (my favorite) or some other penetrating oil.
2. While it's soaking, go find a small block of wood. About 1" square should work.
3. Drill a hole in the wood block slightly smaller than the diameter of the gas tube about 1/4" from the edge of the block.
4. Cut the wood block in half directly through the hole you drilled. (You should now have two pieces of wood, a mirror image of each other)
5. Place the wood blocks around the gas tube so the tube runs through the hole you cut in the block.
6. Tighten together with a C-Clamp and wiggle back and forth while pulling back on the block/clamp.
Or if you have time and money to spend, order the Gas Tube Wrench from Bushmaster for $29.95. It accomplishes the same thing.
www.bushmaster.com/shopping/gunsmith/mbc-01.aspGood Luck!