I'm putting together a RRA M4 upper. The gas tube is tight going into the front sight tower. Is this supposed to be tight, are you supposed to tap it in or?

I've had a few go in tightly. A little CLP will help things along. Make sure you're not installing the tube upside down.

If it's a new upper, you might try deburring the sight tower with a hand held drill bit. Same for the gas tube pin hole on both sides. If it's an older upper and you're only replacing the tube, give it the same drill bit treatment to remove carbon buildup. The tube is supposed to be tight as that prevents gas escaping, but not so tight that you can't work it in by hand without tools. Suggestion for CLP use is good too. You are inserting the tube into the upper and then into the sight tower next, right?

What ever you do don't tap on the end of the tube that contacts the gas key of the bolt carrier.  Any deforming of this end could lead to reliability problems.  When a gas tube is installed in a new sight block there is usually ample room to insert it, stress free.  After a dozen shots or so carbon build up fills in the gaps and seals it.  If you then remove the gas tube it will be pretty tight when inserting a new one.  Cleaning out the carbon with a bore brush and CLP is an option.  For removing and installing gas tubes I have used a set of small vice grip pliers.  I lightly clamp the tube near the end that goes into the sight block.  Then I tap on the pliers just above the gas tube.  This works very well and doesn't damage the gas tube.  For putting them back in I coat the end of the gas tube with CLP and tap lightly on the pliers.

[img]http://www.brownells.com/Images/Products/133100016b.jpg[/img]

[url=http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=1851&title=AR-15%2fM16+TOOLS]Gas tube wrench[/url]

Lacking in proper design but it works.

Yeah, Tweak, this is one of those tools that I thought I could do without (you can't buy EVERYTHING in the Brownell's catalog) until I somehow manged to trade for one. Now I wouldn't be without it. I've only found one gas tube that was so carboned up I couldn't remove it with the tool, and installing a new tube is much easier too.

Ditto. I do a lot of on the range and when a tube sticks a vise isn't an option. Using it is a lot less hassle than Vise Grips, pliers or plain old tugging. I never realized how much time I was pising away not having the proper tool.