View Full Version : AR bolt question

05-16-2011, 10:52 PM
Looking to build a precision AR for 5.56/223. Browsing White Oak Armament website at their barrels and notice they offer "Headspaced bolts" with their barrels. Please school me (always looking to learn) on getting matching bolt and barrel vs just buying a complete BCG (lets say LMT or BCM) and using it on a different brand barrel. Is this any advantage? I understand headspacing is important on bolt guns how but about on the AR platform?

Thank you in advance,

05-17-2011, 1:45 AM
This topic has been around for so long regarding AR platforms and headspacing.

As a military armorer let me give my experience and opinion on this topic.

Let me say again my opinion...

Its not needed. Plain and simple. Actually Don't worry about it, the headspace on a AR type rifle is set by the barrel extension, which is the part the bolt engages with it's lugs. This is different than a typical bolt rifle, which the bolt engages lugs in the reciever and the barrel is screwed to that. The barrel extension on a AR rifle is set at the factory on the barrel at the correct distance and headspace so you can install it on any upper and not worry about it. And use any bolt from any manufacture and not worry about it....so on...

Ive used USGI bolts in Bushmaster carriers in M4s with no problems. Used bushmaster bolts in USGI carriers with no problems etc....

On a deployment I had this supply Sgt from another company always telling me to headspace the M4's. Man was that irritating even though it did say in the TM that Bolt assemblies, and/or barrel assemblies may be interchanged from one rifle to another, If these parts are interchanged the rifle must be checked/inspected. While performing these checks and inspections, pay special attention to the headspace requirements. From experience and schooling I had enough and called a rep from Bushmaster I knew at the time since he sent me a crapload of parts for our deployment. Anyhow his Smithy's there at Bushmaster said exactly what i quoted above..

Again IMHO go ahead and use whatever barrel with whatever bolt. But if there is a headpsace issue than I stand corrected.

05-17-2011, 3:37 AM
What Milspec said, use quality parts and you will almost never run into any issues, I would imagine you stand a better chance of winning the lottery than to experience problems.

05-17-2011, 6:15 AM
What are the symptoms if headspacing is required?

05-17-2011, 6:27 AM
If the headspace is too long you 'll see excessive case stretching and in the worst case- case seperation.

If headspace is too short then your gun will have difficulty chambering spec ammo.

With mass produced (even Milspec) you have a few thousandths (or tenths of thousandths) tolerence for the bolt assembly and the barrel extension so you can have a couple of thousandths of difference in the matchup. What companies like White Oak Armament do is measure and match up bolts and extensions to minimize this difference.

05-22-2011, 7:45 PM
Bottom Line... Take it to a smith to get it head spaced if your having issues.

06-10-2011, 11:02 PM
If I'm installing a barel and bolt on a different reciever than they came with do i need to worry about headspace.

06-10-2011, 11:06 PM
For an AR the receiver has nothing to do with the headspacing.