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AR15.COM
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12/11/2009 10:30:03 PM EDT
do you head space the ar 308 types the same as the AR 15/m16's ?

thanks for replyies
12/12/2009 4:38:45 AM EDT
[#1]
In short, yes.

In fact, you check head space in all rifles using the same basic procedure.

Remove extractor & ejector from bolt,
place lightly-oiled gauge in ultra-clean chamber,
attempt to close bolt with finger pressure only.

No forcing the bolt down on a bolt action,
no dropping the bolt with a semi-auto from full retraction.

Finger pressure only ... period.

MLG
12/12/2009 4:55:05 PM EDT
[#2]
so you can not change headspacing .. you just replace parts barrel if head spacing is wrong.
12/13/2009 11:17:23 AM EDT
[#3]
Yes, you can adjust headspacing on an AR-15, but it's a pain in the ass.
You have to remove the barrel extension and machine back the barrel shoulder so the extension can make exactly one complete rotation, leaving the gas port back at top dead center.
Then you machine back the barrel root and rechamber.  Usually there is enough play in the gas tube and key that it will work.  Other times, you might have to trim back the gas tube a bit.

Tony

12/14/2009 1:01:22 PM EDT
[#4]
do you do the ar 10 the same as ar 15 .  lets leave out the rechambering and removing barrel extension..  that is only for those with machines to do the work.   does the average person just change the barrel or bolt  for new.. or even change both to get head spacing  or is it cheaper to send old barrel off to have it re chambered and head spaced..  since barrel for ar10 seems a little more costly
12/14/2009 2:18:03 PM EDT
[#5]
Quoted:
do you do the ar 10 the same as ar 15 .  lets leave out the rechambering and removing barrel extension..  that is only for those with machines to do the work.   does the average person just change the barrel or bolt  for new.. or even change both to get head spacing  or is it cheaper to send old barrel off to have it re chambered and head spaced..  since barrel for ar10 seems a little more costly


All the procedures for barrel headspace etc are all the same between AR-15 and AR-10.   The important thing is that all the chambering and headspacing is done AFTER threading, installing and pinning the extension  and BEFORE drilling the gas port.   A 308 is more expensive due mainly to economy of scale:  they make millions of AR-15 barrels and only thousands of 308s.

As Tony said, while possible, modifying the headspace or rechambering may be possible, but not worth it.   The best way is to start with a barrel and bolt from a reputable manufacturer, and it will all work fine.
12/14/2009 9:21:55 PM EDT
[#6]
Quoted:
In short, yes.

In fact, you check head space in all rifles using the same basic procedure.

Remove extractor & ejector from bolt,
place lightly-oiled gauge in ultra-clean chamber,
attempt to close bolt with finger pressure only.

No forcing the bolt down on a bolt action,
no dropping the bolt with a semi-auto from full retraction.

Finger pressure only ... period.

MLG


before I bought my own gauges I had a dumbass gunsmith helper slam the bolt closed on one and it took a piece of wood and a hammer to get it to release.  Needless to say this was the last time I used that gunsmith!!!  Follow the above directions and the instructions that come with a set of specific headspace gauges.
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