AR Head Spacing

I have never checked headspace.
I don;t know anyone that has.

As stated, pretty much all the parts are the same from the get go.

If you are putting together a gun with a 20 year old worn out bolt and a high mileage barrel of unknown manufacturer. Sure, get some gauges.

If you have quality parts.... you are good to go.

I have stated elsewhere. Brownells makes those videos to SELL Parts and the Tools to install those Parts. Imagine that.......
 
If there is insufficient headspace, and if the bore is not chromed, a reamer could be used.
Click to expand...

Even if the bore is chromed, providing that the chrome job is done properly, you don't have to worry about chrome flaking off. Hard chrome doesn't flake like 'bumber/soft' chrome does. Obviously, if the chrome was not applied correctly, you're going to have issue regardless of if you ream it or not.
 
rivetc78 said:
I have never checked headspace.
I don;t know anyone that has.

As stated, pretty much all the parts are the same from the get go.

If you are putting together a gun with a 20 year old worn out bolt and a high mileage barrel of unknown manufacturer. Sure, get some gauges.

If you have quality parts.... you are good to go.

I have stated elsewhere. Brownells makes those videos to SELL Parts and the Tools to install those Parts. Imagine that.......
Click to expand...

From what I've read this seems pretty standard.

If there is a headspace problem - where does the problem usually take place?
 
sithinside said:
From what I've read this seems pretty standard.

If there is a headspace problem - where does the problem usually take place?
Click to expand...

From out of spec parts.
Reputable manufacturers like LMT, Colt, BCM, CMT/Stag are all generally within specs (confidently)
Although mixing and matching different manufacturers hardware could theoretically cause issues, using above mentioned manufacturers shouldn't cause issue. BUT, there is always a chance you get an out of spec part.

Using worn, or broken in bolts and barrels is another issue entirely. Get the gauges, they are cheap, and check the headspace. The chances you have too much headspace that can cause a catastrophic failure is a lot higher than using new parts.

Do not take an idiots advise never to check headspace. Its good piece of mind for a few minutes work and a few bucks in tools.

I build and rebuild AR-15 platform carbines and rifles for a training agency. I have seen some varying degrees of headspace within and outside of spec. CMMG was one we had issues with. Usually too tight.
We check every barrel/ bolt that goes out to the field.
 
One thing to note is that .308 Ar's are not milspec and should always be matched either by brand or chambered to suit the bolt you are using. Krieger will not ship a chambered .308 and will not chamber one unless you supply or buy a bolt from them. For doing builds Armalite told me that if you use an Armalite barrel to use an armalite bolt, or say a dpms barrel should use a dpms bolt, because there are a few thou discrepencies between the various makers. If you are going to mix and match checking headspace is a must.
 
I have personally experienced one incident of a factory barrel/extension that required selective assembly using different bolts.
I know of one other case on CGN of selective choice of bolts being required to get xorrect headspace.
It is not common, but it happens.
Keep in mind that slightly excessive headspace is not a major issue. Insufficient headspace can be more of a problem.
 
Excessive headspace will lead to decreased brass life if you reload. Very excessive headspace can lead to case head separations but we are talking VERY excessive.

Decreased headspace may not allow rounds to chamber or the bolt to lock (don't worry, the firing pin can't hit the primer if the bolt isn't locked).
 
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