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Head space nightmare 5.56 NATO

7.62x39Lover7.62x39Lover Member Posts: 3,939 ✭✭✭
edited December 2013 in Ask the Experts
Hi guys.

I spent months getting the parts together to build an AR-15. I get it all together, and both the "go" and "no go" guages are a no go.

The "go" guage was so close that I had a stroke of stupidity and decided to load the "go" guage like a round through the magazine.

It was a go, but I had to hammer the bolt carrier out with a punch.

Should I even bother getting a "field" guage to try it out? I dare not try a live round. The "go" guage just barely does not go. Perhaps I should buy a bolt carrier that is manufactured by the same company as the barrel?

Please tell me what you guys would do to remedy the situation.

Thanks in advance.
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Comments

  • tsr1965tsr1965 Member Posts: 8,682 ✭✭
    edited November -1
    Well...the easiest way to head space it, is before the barrel is installed into the upper receiver. Did you purchase the barrel, and barrel extension as an assembly, or separate? The only items you will need to set the headspace with, are the bolt, less the carrier, the barrel, and barrel extension. Then install the already headspaced barrel, and extension, into the upper.

    Best
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  • asphalt cowboyasphalt cowboy Member Posts: 8,904 ✭✭✭✭
    edited November -1
    Field gauge is even longer than the Go gauge. A field gauge is the last ditch effort to keep rifles in use during the heat of battle. IMNSHO they have no use in sporting rifles.

    I certainly hope you didn't let the bolt fly forward as it chambered the gauge. The gauge and or chamber might be damaged.

    You ain't gonna like hearing this, but, remove the barrel and strip the bolt, then check headspace properly.
    You're not going to get a correct gauging with the ejector and extractor in the bolt. Insert the gauge into the chamber and turn the bolt to the locked position by hand. You should not meet any resistance with the Go gauge. The No Go gauge should not even turn in.

    btw, the bolt carrier has nothing to do with headspace. Proper headspace is determined by the locking lugs of the bolt and barrel extension.

    The Field gauge is even longer than the No Go gauge. If it won't close on a Go gauge there's no way possible it will close on a Field.
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  • p3skykingp3skyking Member Posts: 23,916 ✭✭✭
    edited November -1
    quote:Originally posted by asphalt cowboy
    Field gauge is even longer than the Go gauge. A field gauge is the last ditch effort to keep rifles in use during the heat of battle. IMNSHO they have no use in sporting rifles.

    I certainly hope you didn't let the bolt fly forward as it chambered the gauge. The gauge and or chamber might be damaged.

    You ain't gonna like hearing this, but, remove the barrel and strip the bolt, then check headspace properly.
    You're not going to get a correct gauging with the ejector and extractor in the bolt. Insert the gauge into the chamber and turn the bolt to the locked position by hand. You should not meet any resistance with the Go gauge. The No Go gauge should not even turn in.

    btw, the bolt carrier has nothing to do with headspace. Proper headspace is determined by the locking lugs of the bolt and barrel extension.

    My first thought was that the extractor was still installed. You might woiuld like to try it without the extractor. Don't be surprised if everything works then.
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  • 7.62x39Lover7.62x39Lover Member Posts: 3,939 ✭✭✭
    edited November -1
    I installed the barrel onto the upper and tried to head space it with the bolt without the ejector and extractor. Go was really really close but no cigar. I figured the rason it eas not going was because of the awkward way I was able to handle the bolt with the upper attached to the barrel. I will try a field gauge and keep you guys posted. I will order one asap. I will also inspect the guage and barrel for damage.
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  • p3skykingp3skyking Member Posts: 23,916 ✭✭✭
    edited November -1
    If you're using new parts, there may be a slight resistance. This is normal. The parts need to mate in with each other and they do that by being cycled. This isn't rocket science, it's pipefitting.
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  • Tailgunner1954Tailgunner1954 Member Posts: 7,734 ✭✭
    edited November -1
    quote:Originally posted by 7.62x39Lover
    I will try a field gauge and keep you guys posted. I will order one asap. I will also inspect the guage and barrel for damage.


    WHY order a FIELD???????????
    GO is the minimum spec
    NO-GO is +.007 (normally) longer than the GO, and considered the max for assembly purposes
    Field is +.014 (normally) longer than the GO, and is considered the longest that can safely be fired (with minimum length ammo)

    If the bolt is not closing on the GO, than what the hell do you think it will do with a FIELD?

    Ammo is ALWAYS shorter than minimum, with it's spec normally running -.001 to -.008 shorter than the GO gauge spec
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  • 7.62x39Lover7.62x39Lover Member Posts: 3,939 ✭✭✭
    edited November -1
    You're right. Silly me. What do you figure the chances of me having to pull shards of aluminum out of myself are if I try this thing out at the range from the hip?
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  • MobuckMobuck Member Posts: 14,161 ✭✭✭✭
    edited November -1
    It's not such a big deal. I've assembled 5-6 using mix-n-match bolts(new) and so far have not had any issues with excess headspace. You likely caused more problems by slam loading the gauge than would have been present otherwise.
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  • 7.62x39Lover7.62x39Lover Member Posts: 3,939 ✭✭✭
    edited November -1
    quote:Originally posted by Mobuck
    It's not such a big deal. I've assembled 5-6 using mix-n-match bolts(new) and so far have not had any issues with excess headspace. You likely caused more problems by slam loading the gauge than would have been present otherwise.


    The issue is an ever so slightly tight head space.
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  • charliemeyer007charliemeyer007 Member Posts: 6,572 ✭✭✭
    edited November -1
    I'd use a lanyard on those first few rounds. Gauges are hardened steel and have indeed damaged chambers when forced home on bolt action rifles.
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