checking head space

[308reloaded]

I have all the gauges  but would like to know the proper method to check headspacing on the DPMS  LR 308. 

[98Z5V]

Go, No-Go, and Field?  Those are the 3.

On a semi-auto, lock the bolt to the rear when you're inserting the gauges, but don't ever use the bolt release to close the bolt on the gauge being tested.  Ride that bolt forward slowly until it contacts the gauge.  Use your thumb on the bolt carrier to seat the bolt onto the gauge/in the chamber.

Go should close, No-Go shouldn't close.  If the No-Go DOES close, use the Field gauge.  If your rifle closes on the Field gauge, you need some professional armorer help.  Typically, Go and No-Go are the ones used, unless you're working with/testing an in-service weapon, militarily speaking.

[308reloaded]

Am I correct that these should headspace correctly if all parts are new, like  the smaller AR15's  we can not adjust headspacing without machine work.  if the headspacing is in correct it is because part is wrong. either the bolt or the barrel

and do we need to take bolt apart when we check headspacing?  I have all 3 headspace gauges,

[imschur]

We verify headspace because of manufacturing tolerance errors. It's better to be safe than sorry. The 308 has the potential for a lot of damage. AR-15's and used weapons of any type should be verified. I understand many guys have trust and blind faith in the work of others. I feel it's cheap insurance to check every build.

Remove the extractor from the bolt.

This DVD explains and demonstrates headspacing an AR-15. Warning though it will cure insomnia.

You are correct, we cannot "adjust" headspacing

Nice to see someone paying attention.

[308reloaded]

I was checking for answers I already knew but wanted confirmed:

plus I never fire anything I have built without doing check on headspacing.

  this will be my 4th 308win. build but first on AR plate form,  2 fnfal. 1 re barrel of 110 savage which shoot sub MOA , good for such a cheap build, and now this LR308.

[308reloaded]

is extractor easy to remove without any special tools. I bought a tool for the AR then found I didn't really need it.

[98Z5V]

if the headspacing is in correct it is because part is wrong. either the bolt or the barrel

Or the barrel extension.

is extractor easy to remove without any special tools. I bought a tool for the AR then found I didn't really need it.

Use the tip of the firing pin to push the retaining pin out, and the extractor will drop right off the top of the bolt.  Push the extractor inward with your thumb while pushing it's retaining pin out.

[Matt.Cross]

Use the tip of the firing pin to push the retaining pin out, and the extractor will drop right off the top of the bolt.  Push the extractor inward with your thumb while pushing it's retaining pin out.

Gotta make a demo vid on YouTube bro, anything else is so 2010....  ;)

[survivalshop]

We verify headspace because of manufacturing tolerance errors. It's better to be safe than sorry. The 308 has the potential for a lot of damage. AR-15's and used weapons of any type should be verified. I understand many guys have trust and blind faith in the work of others. I feel it's cheap insurance to check every build.

Remove the extractor from the bolt.

This DVD explains and demonstrates headspacing an AR-15. Warning though it will cure insomnia.

You are correct, we cannot "adjust" headspacing

Nice to see someone paying attention.

I think its the ejector you need to remove , to eliminate its spring pressure on the HS gage , as to not give false readings. 

Some of the older or milspec head space gages , you had to remove both the ejector & extractor , but most the new ones have an extractor grove in them .

[6132expert]

Say I got the right upper and BCG and the right barrel but HS is out of wack.

So how do I know what my head spacing is suppose to be? 

What do I do?

I know the common answer would be Take it to a Gunsmith.

What would he do?

[survivalshop]

Send your bolt & barrel to the barrel manufacturer for proper fitting .

I haven't seen one wrong yet.( if properly assembled) I check HS any way.

[6132expert]

OK, great , so when I get everything and fully assy. the rifle and then if I have problems I can just send the bolt and Barrel to the Barrel manf.

Got ya, can a Gun smith also do the fix?

[308reloaded]

the fix on AR type platform.  would be to find out which part...either your bolt  or your barrel with barrel extention on is out of spec.  there is no adjustment, they are built to be within and industry standard,  anything else is unsafe.

hey ask someone how you build a barrel and install barrel extention, everytime I asked elsewhere.it like trade secret and if you dint know how then you no one is willing to tell or teach.. I have even tried to find something in writing.. found nothing Nada. zilch.  if some tells us how to do it, they would have to kill us.

[98Z5V]

hey ask someone how you build a barrel and install barrel extention, everytime I asked elsewhere.it like trade secret and if you dint know how then you no one is willing to tell or teach.. I have even tried to find something in writing.. found nothing Nada. zilch.  if some tells us how to do it, they would have to kill us.

I posted that up here somewhere... 

[survivalshop]

Head space is set when the barrel extension is attached & after it is tested ,its (barrel assembly ) put in a jig to bore the properly aliened gas port in the barrel .

There may be some barrel ID. honing if needed after.

Think of the barrel extension as the receiver or action of a bolt action rifle . They are fitted the same way .

Its just the AR type rifles were designed to just be screwed together & have the proper tolerances.

It still requires the proper tools to do it properly .

[Turbotezza]

This is what I did for my DPMS bolt and Rainier barrel.

1) Removed bolt from carrier, took out the ejector and extractor.

2) Put a GO guage into the bolt. Holding the bolt upright, lowered the barrel over it and confirmed that the bolt would turn(lock)

3) Did the same procedure with the NO GO gauge and confirmed that the bolt would not turn.

4) Replaced the guages with unfired 7.62mm (Surplus) & .308 (PRVI) cartridges and noticed that the .308 was a much tighter fit.

5) Put the extractor back in the bolt and tried to repeat steps 1) to 4) again, but the bolt wouldn't turn on any gauge or cartridge. Checked the extractor and noticed that the lower section of the extractor groove stood proud of the bolt face, tilting the gauge/cartridge ever so slightly so that it wouldn't sit flat in the bolt. This slight alignment wouldn't let the bolt lock up. With a Dremel cutting disc, I slightly ground down the lower bit of the extractor grove so that it was flush with the bolt face. Tested the guages/cartridges again and confirmed proper function.

6) Put the ejector back into the bolt, the bolt assembly back into the carrier. Assembled the rifle and checked headspace again with the guages, first slowly lowering the bolt carrier over the guages and using the forward assist to fully close, and then checking again by letting the carrier fly forward under the power of the main spring.

As a side note. Rainier barrels are chambered very tight, barely closing on the GO gauge with my bolt and should hopfully be a consistent tack driver.

[imschur]

hey Turbotezza what barrel did you get from Rainier? I wasnt aware the DPMS versions had reached their inventory yet. Your getting me excited

[6132expert]

This may be it on page 6

http://www.rainierarms.com/?page=shop/browse&category=&keyword=barrel&pagenumber=6

And dang what a great price on them.

[Turbotezza]

6132 has got it right.

Mine's an 18" and bought it 3 or so weeks ago when it was in stock.

hey Turbotezza what barrel did you get from Rainier? I wasnt aware the DPMS versions had reached their inventory yet. Your getting me excited

[6132expert]

I am keeping y eye on this on.

[imschur]

Thanks guys

[survivalshop]

I looked at those barrels & only reference I read was for Armilite . I didn't see DPMS any where .

It could be my old eyes.

Using the FA to close the action with a head space gage in there or letting the BCG FLY under buffer spring pressure ,will most likely result in damaged components ,including the head space gage.

Light finger pressure only , to test , if you need more than that ,there is something wrong. (improper head space )

[Turbotezza]

They are out of DPMS extension barrels.

I checked using the FA and flying BCG only after confirming by hand fitting. See points 2) & 3).

I looked at those barrels & only reference I read was for Armilite . I didn't see DPMS any where .

It could be my old eyes.

Using the FA to close the action with a head space gage in there or letting the BCG FLY under buffer spring pressure ,will most likely result in damaged components ,including the head space gage.

Light finger pressure only , to test , if you need more than that ,there is something wrong. (improper head space )

[6132expert]

I looked at those barrels & only reference I read was for Armilite . I didn't see DPMS any where .

It could be my old eyes.

Using the FA to close the action with a head space gage in there or letting the BCG FLY under buffer spring pressure ,will most likely result in damaged components ,including the head space gage.

Light finger pressure only , to test , if you need more than that ,there is something wrong. (improper head space )

Should be this one

http://www.rainierarms.com/?page=shop/detail&product_id=2236

and

http://www.rainierarms.com/?page=shop/detail&product_id=2239

[TacBlade]

So how many of you guys have ever checked headspace on an AR platform and it was not correct? I'm Not saying this does not need to be done, as I do think it needs to be done.  But, I am just wondering what did you do if it was not in spec? Not much can be done?