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Posted: 12/28/2016 3:52:35 PM EDT
| I have a ballastic advantage hanson barrel, stag left hand upper, stag left hand bcg. I am building this for my dad. Put all this together and put the no go gauge in and it fails. Slapped the go gauge in, fails. Try his other left hand bcg, fails. Pull his bolt and check it in my upper, i can spin it with my fingers. Identical setup, just mines right hand. Try my bolt in his, spins. Ive contacted BA about it but i think they are closed for the holidays. But im wandering if this is even a problem or not. His barrel passed with my bolt and his bolt passes with my barrel but not with each other. Ive read alot of conflicting info on headspace, so im not sure if i even need to check with a go gauge or not. All bolts were stripped of the ejector and extractor. |
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When it comes to most necked rifle cartridges, you can obtain 3 different headspace gauges (GO, NO-GO, and Field).
The "GO" gauge is for checking for the minimum amount of headspace for the cartridge you are wanting to shoot. You should be able to obtain bolt lock on a "GO" gauge. If you do not obtain bolt lock on a "GO" gauge, then you do not have enough head space to allow the cartridge casing to expand, which can result in over-pressure and primers popping rearward, or the gun blowing up. The "NO-GO" gauge is basically an intermediate gauge that is between minimum and maximum. If you can obtain bolt lock on a "NO-GO" gauge, generally you are still safe to shoot, though the looser chamber can result in shot groups opening up a little. The "Field" gauge is for checking the maximum amount of headspace. If you obtain bolt lock on a "Field" gauge, then you should stop shooting and deadline the firearm. If the headspace has eroded so it's too long , you can have the barrel & bolt replaced (Generally most AR15 type upper receivers, and bolt action rifle receivers can be reused). CY6 Greg Sullivan "Sully" SLR15 Rifles TheDefensiveEdge.com (763) 712-0123 |
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Hi Mike,
Thanks. I am unclear on what you mean by fails or it spins. Can you clarify for us? Whether a bolt "passes" or not is too subjective to be useful. On a new build a bolt should close on a go gauge but not on a no go or on a field gauge. On a used weapon a bolt should close on a go gauge , might or might not close on a no go gauge, and is dangerous to use if it closes on a field gauge. I don't know what you would be spinning with a bolt closed on a gauge, unless maybe you are saying the bolt will close? The bolt, with ejector and extractor removed, will either close and engage or not. Most of the time the dimensions of the extension chamber and bolt will allow the bolt to close on a go gauge but not to close on a no go. this is usually true across many manufacturers because the dimensions are known and the manufacturing has become standardized, so almost anything goes together. But, as you have experienced, sometimes the differences really do make a difference. Many manufacturers of higher end barrels will match a bolt to the chamber for exactly the reason you have discovered. If you can switch out bolts to make the go-no go relationship work, you should be good. If you have a problem child chamber or bolt, the manufacturer should know about this and make it right. Hope this helps. Keep posting. Best, Rick |
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To add to the above, when you are using field gauges, you need to ride the charging handle back down, and use the FA to slowly close the bolt on the gauge.
If you are sling shot'g the bolt on the gauge to close the bolt, is possible to get a false reading isntead!!! |
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