AR-15 ground up build.....head space check?

[cpy911]

Hi,

I am building an AR-15 from ground up. It is more along the lines of a budget build though.

The barrel is AR-Stoner/ESS from Midwayusa.com and the bolt is PSA M-16 Full auto MPI mil spec.

My question is, do I need to do a head space check with the barrel and bolt combination? I hear some people don't as the barrel extension already sets the head space.

If I need to check it, is this easier to do before the barrel is installed or after? If I need to check it, any place local to rent Go/No Go gauges?

What have you builders done?

Thanks.

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[Brutus57]

My 1st and only build had a complete upper barrel and receiver combo from Bravo Company. I'd suggest talking to a local gunsmith if you have one in the area just to be on the safe side.
Ymmv.
Brutus

 

[jonn5335]

I've built ARs and never checked the headspace. I always fire one round and inspect the case and if it is in spec I run the whole mag and inspect the brass every couple shots or so to make sure it's still in spec.

 

[cpy911]

I've built ARs and never checked the headspace. I always fire one round and inspect the case and if it is in spec I run the whole mag and inspect the brass every couple shots or so to make sure it's still in spec.

Is there a spec for fired brass?

 

[Velzey]

You can tell allot by looking at the spent shell. But if you dont know what your looking for, that makes it hard. Any gunsmith can check the headspace of an AR in a matter of minutes.

I have never seen a fresh build be out of spec. Only a few that had seen 1000's of rounds.

 

[uban77]

There are( go,) and ( no go gauges,) you can buy. Inspecting the brass is always a good deal. Check to see if the primer has backed out. Check to see if there's bulging in the case. Check to see if the case is clean, or black. Check to see if you have pierced primes.

 

[nrc]

If the bolt and barrel are both new and from a reputable source - you'll be fine.

 

[Rick4070]

Contact 4D reamer rentals, they rent chambering reamers and headspace gauges, I'm pretty sure that they will just rent the go/no go gauges, IIRC, the cost is $8 for the gauges, plus an $80 deposit that is refunded when the get their stuff back

 

[SON*OF*LIBERTY]

There is no need to check headspace on a rotational locking bolt. The locking bolt mechanism could be considered "automatic" when closed and locked.

"GO/NO GO's" are great for a non locking bolt mechanism however.

 

[Velzey]

Automatic as in headspace is set by the rotational movement of the bolt head?

Ive seen mg34's with well worn bolt faces and a nogo will rattle around in there. I've also seen AR chambers reamed to deep that the bolt head rotates closed and once again the novo will rattle around in there.

 

[cpy911]

Update. I was very careful to inspect empty brass looking for ANY problems and have fired over 100 rounds with no ill effects. I suppose everything is ok. I must be the 99% lucky ones.

 

[SON*OF*LIBERTY]

Automatic as in headspace is set by the rotational movement of the bolt head?

Ive seen mg34's with well worn bolt faces and a nogo will rattle around in there. I've also seen AR chambers reamed to deep that the bolt head rotates closed and once again the novo will rattle around in there.

Hard worn compnents come in for mg34 builds and even cam lock mg42's, that cause issues related to head space, but this is not a build concearn, this is a maintinance concearn.

We manufacture our MG34's from new billet receivers and we source or manufacture compenents to spec on bolts.

However, comparing a belt fed gun is apples and oranges to an AR.

But key being "ground up build with new components".

NOt trying to brag, but a point to prove is that i have literaly built thousands of AR's and have yet to have a "headspace" issue on a build. I spec my parts and teach my guys to spec there parts.

I have also repaired similiar numbers and have not received a "worn bolt face, causing out of battery or rear-ward displacment of the case". Not that I haven't seen some funky chambering issues.

Essentialy your bolt will not lock all the way forward if there is an issue (not related to a mis spec'd case or dibris), but at the time would be related to out of spec parts and thus a QA issue. ALWAYS spec your parts prior to build.

Another postive issue of the design is that if it is a true shoulder/rifleing gap issue (maybe from a bad chamber), it will discharge in a locked bolt which is in itself not catastrophic.

You do want to be concerned with collision timing if it is a gas piston system despite the locking mechanism, you want it to be smooth and not slam in and out of the barrel extension.

Again, all of this , of course, is opinion of experience and we all have our own opinions and experience...

 

[Velzey]

Allot of guys have no idea how to inspect parts prior to a build or even where to find prints!

I guess I have been the lucky one, I to have built thousands of AR's and have had a few dozen with headspace issues. Allot of folks think it's a none issue with an ar but with a mix of parts mfg you can get some interesting results.