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Posted: 1/9/2003 8:27:39 PM EDT
| Alright, I've decided to attempt my luck at building my next AR. From a couple of posts I've read, the lower is fairly easy with no special tools. But I couldn't find much about the upper. I'm probably going to be mounting a 16" Bushy barrel kit to a A1 Upper reciever. Any hints or suggestions to help me out? How do you do the headspacing thing? I haven't purchased the barrel or the Bolt + carrier but I do have the upper on it's way. Do I need any special tools? I have a vise, basic tools (punches, hammer, plyers, etc.) I can pretty much understand the building of an upper, I just wonder about the headspacing thing. How do I adjust? or is everything good as soon as it's put together? Thanks in advance. |
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I guess all the builder's were asleep when you posted. I've only put together one myself. Maybe someone more knowledgeable can give a better rundown on tools. 1. AR armorors wrench or AR multitool and a torque wrench ( the military manuals use multitool and torque wrench. 2. Molylube for barrel nut (some people have used lithium grease or Ultimalube) 3. patience 4. Headspace gauges (I borrowed some, I am too cheap) There are a few other tools that might make it easier but these are the basics. As stated earlier, someone with more experience might have more specifics for you. Good luck and enjoy. |
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Headspacing is set at the factory when the barrel extension is attached to the barrel. It's a good idea to check it to make sure that you didn't get a bad one or have a bolt that is out of spec. That does happen but it's rare. If you don't want to buy a pair of gauges (GO and NO-GO) and don't know anyone who will lend them to you, pay a friendly gunsmith to check it before you test fire the rifle. The only adjustments you could make would be to replace your bolt or return the barrel assembly to the manufacturer for a replacement, depending on which part is out of spec. I recommend getting an armorers' block to hold the upper receiver when you attach the barrel assembly. It's much superior to a barrel vise for that operation because there is less of a tendency for the registration pin (on the barrel extension) to dig into the side of the slot in the upper when you apply torque. See [url]http://www.bushmaster.com/shopping/gunsmith/om-003.asp[/url]. If money is an issue you could probably improvise one from soft wood, but be careful not to crush the upper. |
| They come with directions (which is nice). Really, you can get by with just a "Field" gauge. Brownell's carries them for about $15. Some of them you can check with an assembled bolt, others the bolt is supposed to be stripped of the extractor and ejector. If the bolt closes on it, don't shoot the rifle. If you buy the barrel and screw it on the upper, you can go to a gunshow and try different bolts with the barrel (and your gauge) to make sure the headspace is OK. Basically, when the military inspects the rifles and they get one with excessive headspace to fix it they start by swapping bolts with other rifles. |
| I used the Go and No-Go gauges when I built mine. I took the extractor and ejector off the bolt then put the guage in the chamber and pushed in the bolt minus the ejector and extractor. The bolt should close all the way on the Go gauge and should not close all the way on the No-Go gauge. I got my gauges from Bushmaster and they come with Instructions telling you how to do it. |
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Quoted: 1. AR armorors wrench or AR multitool and a torque wrench ( the military manuals use multitool and torque wrench. I won't argue with this, but here's a tip - get a couple of barrel nuts; clean barrel, nut, & upper very good (remove burrs, break all sharp edges, maybe make a pass with a fine file); use the nut that screws on hand-tight with a spike in the middle (or just at the beginning) of the gas tube hole; lube it; then torque it a couple times (some say three). You may have to try a couple different nuts to get the hole to line up between the spikes @ 30 #/ft. I've read here that some have gone *way* beyond the 30 #/ft spec, but remember that this is a steel nut on aluminum, and once those aluminum threads are deformed, they strip real easy... Barrel nuts are only $3 - $4 apiece; if you & your buddy pool your nuts (bwahahaha!), you should both get lucky... [:D] |
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Quoted: I recommend getting an armorers' block to hold the upper receiver when you attach the barrel assembly... Please note - there are hard plastic blocks being sold at gun shows that *do not* have the inner reinforcing rod. This ~1" dia rod keeps the upper from being crushed. If you buy this block, get a hard material measuring ~1" dia to reinforce the upper before clamping it in your vise. Also, the one I purchased ($29 no-name; has smiling/masked "sunburst" insignia), requires removal of the ejection door assembly, and even then the two block halves don't mate precisely - some material needs to be removed to allow them to close cleanly. All in all, you're better off with the ones from the pros (like California_Kid advised). |
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