I've built several ARs and have never checked the headspace on any of them. 

 

That said, I'm not a cheap bastard and would buy a Go-No Go set if I should.  I see a lot of conflicting reports on the 'net (surprise, surprise).  Joe Blow gunsmith has built thousands of ARs and has NEVER used a gauge.  Billy Bob Bubbason swears you need to check on every build.

 

What say you AR gurus?

I check them on all builds or when swapping BCG or changing out a barrel. That said, non were out of spec. However, the comfort factor is priceless. Remember you are a gun owner. You must hold yourself to a higher level of safety than the layman. You owe it to yourself and family.

Get a "field" gauge and use it.  If it doesn't close on it your more than 90% sure your GTG.  I mill a relief groove in it and then do not have to take the extractor out to check it.  Use it all the time.  Goes in the range bag just in case.

Unless you are installing the barrel extension onto the barrel, there is no need to headspace.

you said it - you've built several ARs - and you'll most likely build more, so get the gauges...they last forever and you'll have them for this and all your future builds.

Buy reputable barrels and don't worry about it unless you are installing the barrel nut

I check, I like to just be sure.  It takes all of 5 minutes to do