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Head space on an AR upper?

A

ARAK

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Gentlemen:

I recently have had a pre-ban Colt upper, without the BCG, come into my possession. In your considered opinion, will I need to do a head space evaluation (removing the ejector, etc.) on any new BCG I obtain before going forward and completing this project? This is my second AR build. The upper for the first build was completed so no problem. Any suggestions/ assistance would be appreciated.
 
Tie string to it and test fire it .. Or find a friend willing to shoot it. I used Loki for that with a mosin.


If you don't want to take the chance there's nothing wrong, buy a gauge or call a few shops to see if they can check . I didn't check the head space on my ar. If I have a good barrel and a good bcg from a good company I wouldn't worry, but its ur face .
 
warwickben said:
Tie string to it and test fire it .. Or find a friend willing to shoot it. I used Loki for that with a mosin.

If you don't want to take the chance there's nothing wrong, buy a gauge or call a few shops to see if they can check . I didn't check the head space on my ar. If I have a good barrel and a good bcg from a good company I wouldn't worry, but its ur face .
Click to expand...

Such a good friend. As a reward, I'll let you shoot my extra hot SW500 load. [wink]

Sent it from iPhone 5 LTE
 
ARAK said:
Gentlemen:

I recently have had a pre-ban Colt upper, without the BCG, come into my possession. In your considered opinion, will I need to do a head space evaluation (removing the ejector, etc.) on any new BCG I obtain before going forward and completing this project? This is my second AR build. The upper for the first build was completed so no problem. Any suggestions/ assistance would be appreciated.
Click to expand...

Why not just check it? Takes two minutes and you'll know for sure. (You do not have to remove the ejector when you check headspace on an AR.)
 
To the OP I would just say it's always wise to check, the guages are cheap enough. That being said every AR upper I have built has never had a headspace issue...Some have been tighter, some looser but always in spec. You may want to do a little research on 223 vs 5.56 chambers. Depending on what you have and if I am not mistaken the bolt will close completeley in a 5.56 chamber using a .223 no-go guage and still be within "spec". If you don't want to get that far into it just take it to a smith and have him/her check it.
 
1903Collector said:
To the OP I would just say it's always wise to check, the guages are cheap enough. That being said every AR upper I have built has never had a headspace issue...Some have been tighter, some looser but always in spec. You may want to do a little research on 223 vs 5.56 chambers. Depending on what you have and if I am not mistaken the bolt will close completeley in a 5.56 chamber using a .223 no-go guage and still be within "spec". If you don't want to get that far into it just take it to a smith and have him/her check it.
Click to expand...

Thanks, 1903. That's probably what I will do!
 
Arak,

Where are you on the N. Shore? I have a set of gauges you can use to check if you want to meet up sometime this week. Let me know. Shouldn't take more than a couple of minutes if you prep the bolt ahead of time.
 
CLW42 said:
Arak,

Where are you on the N. Shore? I have a set of gauges you can use to check if you want to meet up sometime this week. Let me know. Shouldn't take more than a couple of minutes if you prep the bolt ahead of time.
Click to expand...

With certain gauges, you don't need to take the bolt a part. I don't have to with the Forster gauges I bought.
 
CLW42 said:
Arak,

Where are you on the N. Shore? I have a set of gauges you can use to check if you want to meet up sometime this week. Let me know. Shouldn't take more than a couple of minutes if you prep the bolt ahead of time.
Click to expand...
+1. I have a no go 5.56 gauge, which is all you need to make sure it is safe.
 
If you have a Colt upper with the original barrel, call Colt and cofirm, but when I called about a pre-ban Colt marked with .223, I was told that all rilfes were chambered for 5.56 but the ones meant for the sporting market were labeled .223 so they could be distinguished from each other.
 
MichaelScarn said:
Why is a Go, No-go, AND a field gauge recommended?

Why not just buy a 'go gauge' to see if it checks out?
Click to expand...

Go gauge tests minimum head space. Bolt should close on the go gauge.

No-go tests maximum head space with a safety margin. Bolt should NOT close on the no-go gauge.

"Field" tests absolute max headspace with little to no margin for safety. I don't even bother with a field gauge - if the bolt closes on a no-go I'm going back to the work bench before I go to the range.
 
jasons said:
Go gauge tests minimum head space. Bolt should close on the go gauge.

No-go tests maximum head space with a safety margin. Bolt should NOT close on the no-go gauge.

"Field" tests absolute max headspace with little to no margin for safety. I don't even bother with a field gauge - if the bolt closes on a no-go I'm going back to the work bench before I go to the range.
Click to expand...

It's funny you mention that about the field space gauge. That's what the brownells instruction video tells you to use when testing your BCG.
 
MichaelScarn said:
It's funny you mention that about the field space gauge. That's what the brownells instruction video tells you to use when testing your BCG.
Click to expand...

I would respectfully disagree with Brownells on that point.
 

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