I found this article several years ago when I built my first AR a Grendel, and thought it might help some of the new members, and older members wring the last bit of accuracy out of their builds. One of the first things he talks about is upper receiver to barrel fit and bedding if needed. One thing we continually stress lapping the receiver. LOL
What makes an AR accurate by Robert Whitley
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That list is just one set of parameters that I use when doing a build.
The other involves bolt work, barrel extension de-edging and polishing of the feed ramps, and other hand-fitting tricks. I think Whitley has covered them as well.
The one about the gas tube is usually overlooked by most people when doing a build, but is especially difficult on the RLGS. MLGS and CLGS are much more stiff, with less room for things to go wrong, but RLGS has less port pressure, so is nicer on the action and cyclic rate.
You can build an extremely accurate AR15 that will smoke most of the bolt guns on the range if you follow that regimen in the article.NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
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Originally posted by 65Whelen View PostExcellent read and guidelines when doing a build. I understand everything except #10 Front/Back Bolt Play. Can someone explain what this is and how to correct it if it's over .005?
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Originally posted by 65Whelen View PostExcellent read and guidelines when doing a build. I understand everything except #10 Front/Back Bolt Play. Can someone explain what this is and how to correct it if it's over .005?Last edited by customcutter; 02-03-2016, 12:06 AM.
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There is a "tolerance" in head spacing. I don't have a set of "go" and "no-go" gauges, so I can't measure the difference for you. But the tighter your tolerance is to the "go" gauge, the less slop you have in your chamber. Most "accuracy" builders try for .002" or less. Then as soon as you start firing the gun the threads start "stretching" and seating in, so you get a little more.
Hope this helps, like I said I'm not a gunsmith, just my understanding of how it works.
Here is a quick video, and according to him there is .004" difference between go and no-go gauges.
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