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Posted: 8/23/2005 7:41:10 PM EDT
| Where can I find an on line tech drawing of the muzzle end of an AR15? |
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I suspect that he wants the ACTUAL dimensions for the flash suppressor mounting threads. Most times if you just ask, you get a bunch of replies that really say nothing more than "It's 1/2X28" and NO details as to the actual length of the thread, whether there is any thread relief area at the muzzle or any other information. Those extra details aren't strictly needed, but for some people, the job isn't done RIGHT without them. I've never seen this info anywhere either. Don in Ohio |
The thread dimensions on the muzzle should be 1/2 inch x 28 TPI. The threads should be cut to 0.4995 inches diameter, a length of 0.500 inches with a relief of 0.030 to 0.040 inches. The thread relief diameter should be cut to 0.040 to 0.045 inches below the top of the threads for clearance of the muzzle device. I then cut an 11 degree target crown and e nsure concentricity by using a dial indicator to indicate in the bore of the rifle. This ensures a uniform crown. Hope this helps. Charles the Gunsmith.
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I got a print somewhere, not available to me right now, that shows the thread length to be 0.63" as measured from the muzzle. I'd bet that's 0.625", or 5/8", rounded up, as each new factory barrel I measure has that dimension. As stated earlier, the thread pitch is 1/2" X28TPI. Here's one that shows it at 0.650". Close enough, but different than the print I remember. It also shows the undercut that 1911 mentioned.  |
I would have bet a Franklin on who would post a drawing.....I would have won. |
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Great illustration! I ran a copy of it for my 3 ring binder where I keep that kind of stuff. All this discussion prompted me to measure the only FS I've got at the present time, an 'A1 type. The threaded section is almost exactly .630, but the cavity continues to about .715 If you subtract the area taken up by the lock washer(roughly .175-.180) you wind up with a small cavity between the muzzle and the constriction before you reach the slotted area of the FS. It's right at .250, give or take a couple of thousanths. What I'm wondering is, does that cavity contribute to the effectivness of the suppressor? Why else would they have it there? I suppose that it could have just turned out that way for no particular reason, but I doubt that. Any guesses? Don in Ohio |
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