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Posted: 12/10/2003 8:18:46 AM EDT
I built my 1st AR-15 a week and a half ago and think it's the most beautiful thing I have ever seen: 20" J&T Expeditionary on a Rock River lower. Thanks to the tips and directions I found on this site, the total time was just over an hour; and much of that time was spent reading and rereading the directions so I would not miss anything. I suppose that if I do a few more and get more familiar with it, I could cut the assembly time down to 30 minutes or so (J&T upper was complete).
My questions are about the sights and shooting it. When I sighted it in for windage, I had to move the knob about 20 clicks to the left of the center line. Is this normal? Don't say the problem is with the shooter: I shot it both right and left handed and a friend shot it as well - same bullet placement. Also, is there a break-in period for shooting it? It shot flawlessly with American Eagle, but with a couple of the Russian brands, I had a lot of 'failure to feeds'. The bolt would go back just far enough to eject, but not far enough to pick up the next round. Is this due to a stiff spring that may (hopefully) or may not loosen up or is it just to to the Wolves and bears being too weak to push back the bolt?
Link Posted: 12/10/2003 8:34:29 AM EDT
Welcome to the addiction! My first build was also very satisfying. You WILL build more. [:D] At what distance were you shooting when you were zeroing the rifle? I never had to make any windage adjustments greater than three clicks on any of my rifles. Are you sure the front sight post isn't canted? Admittedly, I'm not real familiar with the J&T stuff. All my rifles are RRA, Bushmaster or Eagle Arms. That said, does the rear sight look to be about centered, or is it adjusted all the way to one side? Regarding the feed issues, it's possible there isn't enough gas being blown back. What kind of Russian ammo did you use? Maybe it was under powered. Was everything cleaned and lubed on the rifle before shooting? What magazines are you using? After the failures, did you go back to the AE ammo and try it again? Come shoot with the GA guys sometime. [:D]
Link Posted: 12/10/2003 9:45:02 AM EDT
My buddies bushmaster has the same sight problem, front sight is not straight. He lives with it.
Link Posted: 12/10/2003 10:22:48 AM EDT
[Last Edit: 12/10/2003 10:26:53 AM EDT by Homo_Erectus]
Originally Posted By u-baddog: My buddies bushmaster has the same sight problem, front sight is not straight. He lives with it.
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No reason to "live with it" when all you have to do is make a small adjustment to the barrel pin notch in the upper receiver. Basically you just open up the notch with a jeweler's file so the front sight comes up straight, then tighten the "loose side" of the notch with a small hammer and punch with the barrel in place to eliminate any movement. If you're going to build a rifle, might as well build it right. Look at [url=http://www.ar15.com/forums/topic.html?b=3&f=4&t=173151]this thread[/url] for complete details.
Link Posted: 12/11/2003 6:47:42 AM EDT
Upon closer examination, it appears that the front sight assembly is about 1 degree off of vertical. I see 2 pins underneath it that look like they can be pushed out, then the sight assembly rotated, then pins pushed back in. This scares me. I just know I would end up with a front sight that spins around the barrel. Would I be able to rotate the whole barrel 1 degree? I'm not too excited about this option either (did not install the barrel to the upper, nor ever have), unsure how to do it. As for the F-T-Fs, the offenders were: Wolf 55gr HP and Silver Bear 62gr SP. The mags are Brittish steel (highly recommended from Ammoman.com)so I doubt the problem was with all 5 of them. I did a pretty decent clean and lube when I assembled the rifle, so I doubt the problem is there. I still think it is a stiff recoil spring and do hope it's just a matter of breaking in the rifle (I've only shot a little more than 100 rounds).
Link Posted: 12/11/2003 7:37:16 AM EDT
While it is certainly possible that the front sight assembly was assembled canted, or the barrel locating pin wasn't set in exactly straight, the usual cause of the condition you've described is that the barrel locating pin got mashed into the left side of it's slot when you assembled and tightened the retaining collar. This canted the front sight just enough to cause the right shooting impact. It only takes a couple of thousanths of being off to significantly alter the point of impact. Pull the barrel, and take a look at the channel the locating pin slides into. My hunch is that you'll see a depression in the left side of the channel. Whether you do or not, see if there is any sideways play between the pinn and the side of the channel. If there is, you need to put a shim, probably .002-.004 on the left side of the channel, and reinstall the barrel. If there isn't any sideways play, then either the locating pin or the channel are slightly off and you should open up the right side of the channel a couple of thousanths, and then put the shim over on the left side. DO NOT screw with the front sight assembly. It's all controlled by the placement of the barrel in the upper. Putting an AR together may look easy. Doing it correctly isn't always as simple as some of the people who post here make it sound [:D]
Link Posted: 12/11/2003 8:10:18 AM EDT
Originally Posted By shamayim: Putting an AR together may look easy. Doing it correctly isn't always as simple as some of the people who post here make it sound [:D]
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Boy, ain't that the truth. [:D]
Link Posted: 12/11/2003 9:06:23 AM EDT
The remedy that Samayim may be above my level of gunsmithing. Remember, the upper came already assembled: all I did was attach it to the lower that I assembled. Would ya'll suggest that I send the upper back to J&T for them to fix?
Link Posted: 12/11/2003 10:41:30 AM EDT
Originally Posted By kmclain: I see 2 pins underneath it that look like they can be pushed out, then the sight assembly rotated, then pins pushed back in.
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The pins, and the grooves they ride in, are tapered. If you rotate the FSB you won't be able to get the pins back in. When you reinsert the pins the FSB will be back at its same, incorrect, orientation. Added problem is that the gas port in the barrel must align with the port in the underside of the FSB. If you rotate the FSB you may occlude the gas port. Send it back to J&T if it's beyond your skill set. 20 clicks is far too much. The standard is 12 clicks (A2 sights) and 6 clicks (A1 sights) with a 100 yd zero.
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