First off, thanks for looking

A couple of months ago you guys gave me some great advice on what spare parts I should have onhand for my two aging preban Colt 6601 HBARs. If you don't mind I have a few more questions:

1) At what point should I start to think about barrel replacement? Do I simply wait until accuracy goes into the toilet? Both rifles have over 10k rounds through them but they are still plenty accurate. I'd like to know if there is a rule of thumb besides waiting for them to "go bad".

2) Which headspace and/or feeler gauges should I buy to facilitate question 1?

3) I've read that the gas tube eventually wears out where the carrier key telescopes over it. Is this true? Should I replace the gas tube only when it breaks or before?

4) Assuming I have the right tools and a headspace gauge is barrel replacement a job that a novice can safely handle, or should I contact a smith? I'm not afraid to tear into my ARs, but if rebarreling is an art form rather than a specific procedure I don't want to screw them up.

5) Is the Marine Corps armorers manual still the best "bible", or is there something better that is geared more toward a casual civilian AR novice?

Thank you in advance not only for your expertise-but also for your patience with my endless stream of questions. I am trying to become more self-sufficient with the technical aspects of maintaining my ARs. That being said I don't want to fubar a perfectly good weapon by getting in over my head.

I'd wait until accuracy just goes bad.  You may have another 10k rounds to go.  There is no "rule of thumb", it's just preference.  I'd guess that most people wait until accuracy suffers.



I'm not sure that you need them as long as your upper was properly headspaced when you got it and you haven't changed bolt carriers, bolts, uppers or barrels.  Maybe someone else can instruct you on this.



I think this might be one of those "it might, it might not" things.  I think it depends on how much contact the carrier key is making with the sides of the gas tube.  If it's perfectly lined up, you might not have any gas tube wear.  My recommendation would be to look at it from the end (rear).  If it looks like it's getting thin anywhere, replace it.  Maybe someone else can weigh in on this too.



Well, I haven't rebarreled, but I have removed my barrel and re-installed it.  Assuming everything works out headspace wise (you won't know until it's together and you can measure with guages) it's pretty easy.  Make sure you have a good barrel or upper vise block, a good barrel wrench, torque wrench and headspace guages.  You might also want something to "shim" the barrel extention alignment pin in the upper so that your front sight post doesn't cant to one direction.  I used some peices of peel washer (used to index brakes and flash suppressors) that I cut up.



I just used the TM, it was straight forward.



Thank you for being clear, concise and having good direction in your well thoughtout questions.

Wyv3rn, thank you for your detailed, well-reasoned and patient reply [:)]

I am slowly gathering the proper tools to service my ARs. I just ordered a DPMS multi-wrench for example as well as a torque wrench. I'm looking forward to learning how to make larger repairs myself.