I want a shorter and lighter weight barrel. Like... 18" or so.

I want it to be very accurate. I have no desire for chrome lined- personal pref.

If I REALLY wanted a barrel, I know exactly what to do- get out the check book, and get in line for a top notch barrel.

Nah- too easy!

How hard is it to move the barrel thingamabob that sets headspace? I mean, for a real AR-smith.

My idea is to pick up a used 20" Hbar, and snick some off the back and accurately rechamber, then snick some off the front end.

Is this a false savings? Should I just buy a barrel blank and have it made to oreder?

Other question- is their any reason a handguard must cover the entire gas tube? Is it a safety issue, somehow?

I'm starting to think a carbine guard withsome gas tube showing might actually look kind of cool.

Pete
(Hey, I'm building a bang-toy, not a weapon somebody's life will hang on!)

It's pretty common to take a 20", have 2" taken off the front and have the gas port opened up, to make the 18" "SPR" barrels. No need to mess with the barrel extension and deal with realighning the index pin and the gasport.
I have had four barrels worked on, and a handfull of parts, by Mike at Ohio Rapid Fire.([url=ar15.com/forums/topic.html?b=7&f=25&t=139752]me223[/url] on the EE!) He has done this type of work on several FAL barrels.

-ed; btw, he would also be able to lighten that HBAR profile.[;)]

I might be beating this thing to death. I'm looking to build an upper that matches an ARFX... know what I mean?

Well if you're realy a Sadist-Masochist and money is no object you can do what you have out lined.  It probably isn't going to be any more accurate or cheaper than to just get a new barrel and have it made to your specs.

What is an ARFX?

Edited to add that the gas tube will get realy, realy hot and like I said above if you like pain....leave it exposed.

Yeah, bring on the pain.

If I wanted another rifle, I would just buy it. Where is the fun in that?

So, I'm trying to put a concept thing together from bargain parts. Notack is providing the ARFX stock set.

The theme is "tubes."

Pete