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Posted: 11/19/2002 9:14:49 PM EDT
| I have built a AK and rebarreled several Mausers . I see that all the adds that AR uppers are headspaced from the supplier . Am I dreaming or is all you have to do is put the rifle together????? Please Reply!!!!!! |
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IF you buy a complete upper from one of the NAME AR15 manufacturers (Armalite, Bushmaster, Olympic Arms, Colt, Rock River Arms, DPMS) then the headspacing has been checked at the factory. If you buy the parts (barrel, upper, bolt & bolt assembly) and assemble it yourself then you need to check headspace. If someone else builds the upper for you then ask if they checked the headspacing. |
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The bolt of the AR locks into the barrel extension, which is part of the barrel assembly. So, the supplier can check these for headspace for you. You can assemble the parts yourself without having to check headspace. You will need certain tools, but yes, you can assemble yourself. It might be better, unless you intend to rebarrel other AR's, to just purchase your upper already assembled. |
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Is this anything close to correct procedure for checking AR headspace? 1. Remove bolt from bolt carrier. 2. Remove the ejector and ejector from the bolt. 3. Drop guage in chamber. 4. See if bolt will engage locking lugs with light finger pressure. What is the fix if barrel/bolt are new and headspace is incorrect? TIA. |
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There is no way to adjust (or mis-adjust) this in assembly. You, the assembler, cannot "set the headspace". I keep hearing this, and whoever these people are that say it, it is obvious they have not barreled an AR. Yes, it is possible to INCREASE headspace, by machining... removing material from the back of the lugs on the bolt, the face of the bolt (possible, but this is not how it is done), or by using a chamber reamer (the preferred way). There is no way to decrease headspace without new parts. This is all beyond the average or even good home assembler, or most gunsmiths. This is machine shop work. The real fix for most of us is another barrel and bolt combination. You can try a few bolts, but usually, if both barrel and bolt are new, you are OK. |
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A_Free_Man is right. The only way to "adjust" headspace is by first replacing the bolt and rechecking. Try several bolts. If that doesn't work you have to replace the barrel. Get yourself a copy of TM9-1005-319-23, the Unit and Direct Support Maintenance Manual. It used to be on old.ar15.com but the link is dead. That link to the old site seems to come and go so try it another time. |
| The AR15/M16, like most military arms, was designed for parts to be replaced in the field, my unit armorers. The parts would have to be held to a tolerance that would allow an armorer to pick any new bolt from a box of bolts, and insert into any rifle, and have it work. |
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Quoted: There is no way to decrease headspace without new parts. Don't need new parts if lathe available. Take barrel extension off, cut just enough so barrel is set back and front site aligns, check headspace and adjust by reaming or trimming extension (on chrome chambers). Index pin can be turned with shoulder to fit or old holes filled and a new one drilled. |
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