Barrel extension shims?

[kurtm]

A few shot of a barrel and extension  I am putting together.

[K-Tex]

4 hours ago, kurtm said:

So K-Tex, are you saying you can change the head space on an AR with a barrel nut shim? That is what you just said above, you need to revisit how it all goes together if you think this.

The extension is screwed on to the barrel, the barrel is headspace to the extension and torqued to around 135-150 ft/lbs, no nut involved! The extension comes with the pin hole already drilled it IS NOT drilled latter. The extension is the part that fits into the upper receiver, not the barrel, so it really goes like this.... receiver, extension, barrel (already screwed on to extension and headspace), shims....if needed (almost never by the way), and then barrel nut. Here is a picture of an extension waiting for a barrel to be threaded, chambered, headspaced, and screwed on.

No, that's not what I'm saying.   Headspace is changed/set by how far the extension is screwed on.   The extension is like a receiver on a bolt gun.   Instal a headspace gauge into the barrel, screw the barrel into the extension, place a bolt into the extension, then adjust the barrel until headspace is met.   Barrel shims is for barrel nut timing as on a Delta ring for gas tube can pass threw.   You might with a different type of shim(s) be able to headspace a bolt?   Not sure on that?   When you go too , let's say (x caliber or McGowan) there a place for checking JPbolt for headspacing.   They will send barrel and bolt used (they used) for proper headspace.   Midway USA sells barrel and bolt together from Shilin as some other companies.

[K-Tex]

If a gas port is drilled latter (could be) then burrs would need to be removed from the rifling.   Maybe the headspace (like you're saying) extension torque then pinned, gas port drilled.   Somehow/way the breach will need too be shaved too get proper headspace (torque extension, check headspace, incorrect headspace, remove extension, shave off .oo2" from barrel, torque extension, check headspace, drill and pin extension, drill port, clean barrel,  add to inventory)?   Maybe?   I have never inquired about procedure.   You might be 100% correct!

[K-Tex]

Maybe they or could shim between the shoulder and extension, but when an extension only is sold with pin hole drilled then what?   How will you headspace and align gas port on a barrel without drilling a new pin hole in the extension?

[kurtm]

Extensions are not "pinned" to the barrel!

 

From my post above, one of us is obviously machining barrel blanks, threading, chambering, setting head space, torquing on barrel extensions and drilling gas ports. I'm not at all confused as to what happens, what steps to do in what order, nor how it is all assembled or correctly head spaced to a bolt, but you have me at a disadvantage! Why would you ever re-drill the extension pin hole when it is installed in the exact place it needs to be from the extension manufacturer?  I am also sure that you have missed two steps in your headspace example if indeed you messed up your measurement while machining the threads and cutting the chamber in the first place. Can you tell me why you do it the way you do it in your shop?

[K-Tex]

1 hour ago, kurtm said:

Extensions are not "pinned" to the barrel!

 

From my post above, one of us is obviously machining barrel blanks, threading, chambering, setting head space, torquing on barrel extensions and drilling gas ports. I'm not at all confused as to what happens, what steps to do in what order, nor how it is all assembled or correctly head spaced to a bolt, but you have me at a disadvantage! Why would you ever re-drill the extension pin hole when it is installed in the exact place it needs to be from the extension manufacturer?  I am also sure that you have missed two steps in your headspace example if indeed you messed up your measurement while machining the threads and cutting the chamber in the first place. Can you tell me why you do it the way you do it in your shop?

You got me?   Extensions are sold individually with a hole and maybe a pin, but headspacing one or how it is exactly done?   I don't know 100%.   Some reason extensions are sold without a barrel.   I buy it complete and ready too drop in.   I've built over 50 ARs (15s and 10s) and have headspace issues with only 2.   Being I had several extra bolts and carriers I solved headspace issue.   I have go and no-go gauges for every cartridge I shoot.   I don't chance anything I shoot and rely on manufacturers too do their job.   Like your statement about extensions are not pinned on the barrel.   Good thing they aren't!   Getting them off would be terrible!   I've never taken 1 apart, so I had no knowledge of if yes or not.   I'll try my google fu for an answer or video on process.

[kurtm]

Ahhh..... You have "assembled" over  50 AR type rifles from parts others built, got it.

 

Extensions are sold separately so someone can take a barrel blank from a blank supplier, turn it to what ever profile they wish, do all the work to thread, chamber, drill gas port etc. and then either assemble their own upper, or sell the completed barrel assembly to someone like you who then assembles an upper. That's why extension are sold separately.

 

[K-Tex]

1 hour ago, kurtm said:

Ahhh..... You have "assembled" over  50 AR type rifles from parts others built, got it.

 

Extensions are sold separately so someone can take a barrel blank from a blank supplier, turn it to what ever profile they wish, do all the work to thread, chamber, drill gas port etc. and then either assemble their own upper, or sell the completed barrel assembly to someone like you who then assembles an upper. That's why extension are sold separately.

 

I've never bought a barrel and extension separate.   I let the other people assemble that part(s).   How they correct headspace was never addressed.   Still unsolved?   For a custom barrel (AR) it's purchased complete with turned gas block journal.   Buying a BA barrel and turning it into/converting AR use. ......no thanks.   Someone else maybe?

[kurtm]

Ahhh, got it! Excruciating, but obviously no concept of the topic, but man, with a key board!!!! Gotta love the experts on the web!!

Edited October 17, 2021 by kurtm

[GrumpyOne]

I don't know much about the subject matter of this thread, but I do know that if the attitudes being posted in it don't change, it will get locked.

 

Posting Guidelines

Attitude
Please be polite. Or if not polite, at least respectful.
No bickering. Regardless of the subject matter.
Antagonistic, offensive, or quarrelsome tones are not acceptable.
No trolling. No alternate accounts.
 

[K-Tex]

4 hours ago, GrumpyOne said:

I don't know much about the subject matter of this thread, but I do know that if the attitudes being posted in it don't change, it will get locked.

 

Posting Guidelines

Attitude
Please be polite. Or if not polite, at least respectful.
No bickering. Regardless of the subject matter.
Antagonistic, offensive, or quarrelsome tones are not acceptable.
No trolling. No alternate accounts.
 

Are you being specific to me?   If in regards to me, but not limited to me I'm not posting attitude.   If basing it off of punctuation marks it could be read both ways?   PM me for further instruction.

[GrumpyOne]

2 hours ago, K-Tex said:

Are you being specific to me?   If in regards to me, but not limited to me I'm not posting attitude.   If basing it off of punctuation marks it could be read both ways?   PM me for further instruction.

I was being specific about the attitudes, not any individual. 

 

As for punctuation, it's the content and how it is said, not the punctuation.

 

For your last point, it seems that no instruction is necessary.