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Posted: 4/12/2004 2:31:26 PM EDT
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Recently, I picked up a copy of the Army and Air Force M16A2 technical manual. Its dated May 1991. The book details assembly and disassembly of the rifle. The manual states repeatedly: "DO NOT interchange bolt assemblies from one rifle to another. Doing so may result in injury to, or death of, personnel." This is the first I've heard of this. Is there something I should know if I need to buy a new bolt assembly? Why would interchanging bolt assemblies be so dangerous? |
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Thanks! I've seen the headspace gauges. Can you direct me or explain to me why the space would be different between rifles of the same make and model? Also, if I buy a brand new bolt from Bushmaster, is this going to be an issue? Sorry for all the questions, I appreciate the advice! |
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Each barrel is individually chambered with a reamer. Headspace is measured in thousandths of an inch. Just varying it one way or another a few thousandths can make it dangerous. Whether you buy a brand new bolt from anybody, it is always prudent to check the headspace when changing bolts. Don't worry about the carrier, but check when changing bolts. More than likely it won't be an issue, but considering the money you paid for the rifle and a potential visit to the ER, don't you want to be SURE? |
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Quoted: Alright...so if I wanted to be safe, should I just buy any entirely new bolt and bolt carrier altogether? I really don't have a good grip on this-even after checking the resources on this site, and I can spare the extra money... If the rifle you have came with the bolt and is factory original, don't worry about it. However, IF you buy another bolt to either keep as a spare or replace it with, have the headspace checked to be SAFE. The carrier has nothing to do with headspace and they can be interchanged without worry. |
| yep,I've heard former vets say that at the range after qualification during cleaning that the shooters would just toss all the bolt carrier assemblies into a tub of solvent and let them soak. When they were retrieved nobody gave any mind to putting any of them back in the rifles. There was no system in place to match bolts with each rifle. I am obsessive enough about safty and have the time so I check headspace periodically on my rifles anyway. It may not be necessary but it gives me peace of mind. |
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I heard as long as your using spec parts and they are all new and not worn, "that there is no problem" is this true? I heard that a used guns, Bolt and barrel extension will wear together. And switching bolts at that point is when you worry about Headspace issues. Is that true? |
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If the parts are in good condition, switching bolts is not dangerous. "Each barrel is individually chambered with a reamer." True, but not headspaced to that particular bolt. The AR-15/M16 is NOT a custom fit rifle. No standard issue military rifle is. I have swapped bolts among my rifles many times, with never a problem. I have swapped bolts and bolt carrier assemblies among my and other rifles doing troubleshooting. Where you should be concerned is in buying parts kits made up from old, worn out M16's. If you have fresh barrels and bolts from reputable manufacturers, you will not have a headspace problem. Overall, the headspace/kaboom problem is way, way out of sync with reality. |
| Back in the 80's when I was in high school I was on the school rifle team and we shot the M16 at the National Guard Armory. When they stored their weapons they kept the bolts locked-up seperate from the rifles. There was no markings on which bolt went to which rifle. They evidently were'nt concerned with headspacing with their weapons. |
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