Greetings everyone,

I just checked headspace on my uninstalled Sionics barrel and bolt.  I used the procedure in the video below.  Since this was the first time I have done it, is it possible to damage the chamber?  I did my best to only use enough pressure to overcome the ejector spring.  I was an auto technician for several years so I do have some sense of feel.  I looked inside the chamber and bore and I didn't see anything obvious but I also wouldn't really know what to look for either.  I think next time I may just disassemble the bolt.  Any other advice?

[youtube]http://www.youtube.com/watch?v=-fJbezHgGBA[/youtube]

Thanks!

Best to remove the ejector first. If possible, attach the barrel to the upper. It doeesnt have to be torqued. put the bolt into the carrier. slide bcg into the upper, push forward. With a GO gage, light finger pressure on the carrier should close the bolt. The back of the carrier flush with upper. Now, with NO GO gage, do the same, except the carrier will stick out the back, about 1/8 to 3/16". Field gage should have the same result as NO GO gage. Barrel alone, with ejector removed, it is easiest to put the gage under the extractor lip first. Put the GO gage and bolt into the barrel. Without any kind of tool in the bolt, you should be able to turn the bolt into battery, or to the next notch to pull the bolt out. Next, with NO GO gage, do exactly the same as with GO gage, except not the bolt should NOT turn with only you trying to turn it. DO NOT use any type of tool in the hole in the bolt. NO tools except for your fingers.

Thanks for advice.  I am not going to do it this way again.  It is not that hard to tear down the bolt.  

While I am at it, when I was torquing the barrel nut on, something fell over in the garage (which surprised me because there was no one else in there with me) and when I turned around to look I knocked my breaker bar into crown end of barrel.  I inspected with a magnifying glass and I didn't see any visible markings so I assume I am in the clear, right?

Edit: I should say that I am not even sure it contacted the unprotected crown.  I don't see marks anywhere.

I have been so excited to finish this build and it is not going how I envisioned it.  I have read and read, watched and watched and the stupidest things are happening now.

Check out my thread from about 2 weeks ago on this subject.

The biggest reason to remove the ejector is so you don't have the ejector in the way.  Without it, it is absolutely crystal clear whether or not your bolt turns in the barrel extension.  It's almost impossible to hurt your barrel with a chamber headspace gauge no matter how much you fumble around.  Just make sure there isn't anything obvious in the chamber (use a flashlight) and wipe out any gunk or preservative oil before you start.

I found checking with the barrel uninstalled to be easier than with everything put together; there's less extra stuff getting in the way or confusing what you're feeling.

Suprised that thread didn't come up while I was searching.  I have read about every other one.  Thanks for linking it though.

OP - I purchased a USGI Field gauge from Bill Ricca:

http://www.billricca.com

They are certainly not cheap but I think its a nice tool to have, even as an investment.  Bill says once there gone...they are GONE.

With the gauge he sells (only has a few left) you do not need to remove the extractor or ejector.  See my pic in this thread:

http://www.ar15.com/forums/t_3_4/656270_Proper_Use_of_a_Chamber_Field_Gauge.html

Last part was me. I should have bought a bargain/truck gun to assemble first. Still happy with it but wish I wasn't in a hurry to shoot it/ get it done.

Sorry for the off topic post.

For sure man.  This isn't actually my first time disassembling and assembling.  I free floated my other ar and everything went lickity split.  I didn't have any of these careless errors.  It probably didn't help that this was my big money rifle ( will big money to me).  All I have left to do is clock the flash hider and I will get pictures up.  My home made barrel blocks did not work so I need to figure something else out.