AR-15 Head Space

[RLara]

[NorCalDustin]

If it has a head-space issue you would need a gunsmith to fix it. Generally speaking, you shouldn't have a headspace issue if you purchase a quality barrel and bolt. Should you check Headspace, yes... Are you likely to have an issue, not with modern machining processes.

The headspace is the space between the bolt face and the chamber.

[a308garand]

"Would correcting out of tolerance head space be something left for a gunsmith? Can anyone point me anywhere to where I can get more information on head spacing? I just want to get a better understanding on this critical measurement. "

The barrel extension is fitted at the factory to the barrel. The barrel extension and bolt are where the correct headspace is gained for your rifle.
The factory sets the barrel extension/bolt interface so that they both fall within accepted measurements to give good headspace with quality made parts. Some gunsmiths build their own barrels and fit the extension at their shop.

If you use quality made parts, they are made to a very high standard and will almost always work with other quality made parts. Mixing worn/used parts with unknown quality made stuff can get you into the area of headspace not being good.

Since the barrel extension is set at the factory, it is hard to remove and adjust. The barrel gas port and things are finished and timed after the extension is installed and they may be misalligned when you mess with the extension.

If headspace has become an issue, the bolt is the part you may wish to "easily" try to make adjustments. Dip into your bucket of bolts and keep trying to find the one that is correct to the barrel.

To correct a "short" headspaced barrel, you could machine a very small amount of metal away from the bolt lugs. While this could be done, the amount of time and effort required is not worth it. Cheaper and easier to ream the barrel to the correct measurement. Even easier to return the barrel to the factory to make them correct the issue.

If your headspace is too long, and a replacement bolt does not correct it, its time for a new barrel. Messing with altering the bolt and firing pin are too much effort as well as costly.

Remember that the AR15 is great for being able to easily swap parts to keep it running. If you have to file/fit parts to get your rifle running, you then have to do it all over again when something breaks.

Having said all that, the vast majority of quaility made parts fit together and are within safe measurement for headspace. You check the headspace as an insurance policy before you start blasting.

If you really want to guarantee you bolt/barrel fitting well, buy them both from the same maker and ensure they have a good warranty or return policy

[kcstott]

The simple answer to correct the headspace on an AR is to use a new barrel.

[RLara]

OK, it sounds like headspace will usually be within specs if parts are purchased from quality manufacturers. But it still needs to be checked to confirm things are within acceptable tolerances. If it’s out of tolerance, follow up with the manufacturer.

I would still like to learn more about headspace for my own education. Can anybody point me to any resources about it.

[JDay]

It shouldn't be an issue if you use quality parts. I've had gunsmiths tell me that in ~30 years they have never run into a headspace issue on an AR platform rifle.

[JDay]

I would still like to learn more about headspace for my own education. Can anybody point me to any resources about it.

Do a Google search, you'll quickly see that it really is a non-issue.

[kcstott]

Do a Google search, you'll quickly see that it really is a non-issue.

Yep pretty much all you do is "Check" headspace on a AR you don't correct it

[ar15barrels]

There is no adjustment.
Parts are either in-spec, or out-of-spec.
If its out of spec, you replace the part.
The first part to replace is the bolt.
If replacing the bolt does not correct it, then you replace the barrel.