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AR mechanics - help please

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  • FisheadgibFisheadgib Senior Member Posts: 5,797 Senior Member
    DoctorWho wrote: »
    Somehow I doubt that you need to remove the gas block in order to do anything to it, while handguards have changed much since I was putting them together, it does seem less likely that the gas block would need to be installed after the handguard is installed.

    Far be it from me to question your wisdom, but you occasionally have to remove the gas block to remove the gas tube, to remove the handguard mount.
    snake284 wrote: »
    For my point of view, cpj is a lot like me
    .
  • DoctorWhoDoctorWho Senior Member Posts: 9,496 Senior Member
    " Far be it from me to question your wisdom, but you occasionally have to remove the gas block to remove the gas tube, to remove the handguard mount."

    Too long out of the game, tis quite true, however, I would dearly love to fix it.......
    "There is some evil in all of us, Doctor, even you, the Valeyard is an amalgamation of the darker sides of your nature, somewhere between your twelfth and final incarnation, and I may say, you do not improve with age. Founding member of the G&A forum since 1996
  • bisleybisley Senior Member Posts: 10,798 Senior Member
    I can't dig in on this project till Tuesday or Wed. - federal jury duty on Monday (plus?) and dentist on Tuesday. Cooking ribs for 13, today.

    I'll post my solution to this cluster**** when I get it solved. Feel free to comment - I'm not sensitive to criticism on this subject. Kinda dreading breaking the news to my grandson that Grandpa has trashed his new rifle.
  • VarmintmistVarmintmist Senior Member Posts: 7,396 Senior Member
    Grandpa can always replace it.....

    Then he would have a extra lower and parts........ darn..
    It's boring, and your lack of creativity knows no bounds.
  • bisleybisley Senior Member Posts: 10,798 Senior Member
    Actually, the upper receiver and barrel are OK for a low end build. A better hand guard system on a properly torqued barrel would be fine for what I want out of this rifle.
  • BigDanSBigDanS Senior Member Posts: 6,973 Senior Member
    For what my opinion is worth...

    That hand guard does not thread on. It is pushed down onto the barrel nut / retainer and then secured with locking screws. As you have already noted, it cannot be turned because of the low profile gas block inside. In fact, it has a channel built into the hand guard that allows it to slide over it. It should just pull off straight away.

    I think if it is stuck to the barrel nut in any way other than by mechanical screws, it has an adhesive that most likely will release with heat. Take a hair dryer on high and heat up the area for a few minutes until it is as hot as it will get it. Pull straight back.

    IMHO

    D
    "A patriot is mocked, scorned and hated; yet when his cause succeeds, all men will join him, for then it costs nothing to be a patriot." Mark Twain
    Alcohol, Tobacco, Firearms and Explosives.... now who's bringing the hot wings? :jester:
  • bisleybisley Senior Member Posts: 10,798 Senior Member
    Yes, but it is not that simple, as I have tried to explain.

    I, too, think that it is supposed to work that way, sort of.

    The 'fly in the ointment' is that there is a screw-on locking ring on the barrel nut that does screw into the hand guard, and it can not be backed off far enough to release from the threads on the hand guard.

    Why? I don't know. I suspect that the barrel nut was supposed to have a washer to space it far enough from the receiver to keep the locking ring free. However it was installed, now it will not un-install in the same manner. The work-around for the correct un-install method is to remove the gas block and spin it (the hand guard), instead of the locking ring.

    I will try the heat. It could possibly get me a little slack that would enable the lock ring to be loosened further, but I'm not optimistic about that.
  • Farm Boy DeuceFarm Boy Deuce Senior Member Posts: 6,083 Senior Member
    At this point once you get the gas block off the worst that happens is you unscrew the entire barrel from the upper receiver.

    IF you do have to trim on the hand guard to get to the gas block set screws you should be able to cover your work up with a piece of rail.
    I am afraid we forget sometime that the basic and simple things brings us the most pleasure.
    Dad 5-31-13
  • bisleybisley Senior Member Posts: 10,798 Senior Member
    Yep, I'll try to 'finesse' it off first, with some heat, and if it doesn't work, I'll get a little rougher with it. I should have time to solve it, today, if Mrs. Bisley doesn't throw me a curve.
  • Diver43Diver43 Senior Member Posts: 10,903 Senior Member
    Were you able to remove the rails? Once off you should be able to access the hex screw on the gas block.
    If not you may just need a dremel
    Logistics cannot win a war, but its absence or inadequacy can cause defeat. FM100-5
  • bisleybisley Senior Member Posts: 10,798 Senior Member
    Haven't tried, yet. The bottom rail has to come off, and I may have to cut a nick out of the hand guard to get at one of the gas block screws. The bottom rail screws were apparently installed with Loctite, so I may have to ruin that rail to get it off. Or, I might be able to cut a slot in the screws that would allow me to use a big screwdriver to break them loose - the hex heads will never survive the torque needed to break them loose, and I don't think the rail will survive enough heat to break them loose.

    I'm going to be as gentle as I can to save the hand guard, but it is coming off, one way or the other. I just look at it as an interesting problem that can be solved with a little time and effort...and a little money if I screw it up. :tooth:
  • Farm Boy DeuceFarm Boy Deuce Senior Member Posts: 6,083 Senior Member
    I am afraid we forget sometime that the basic and simple things brings us the most pleasure.
    Dad 5-31-13
  • bisleybisley Senior Member Posts: 10,798 Senior Member
    I've got you covered on that one, man.

    I bought that identical (looking) rail for my AR, but from Roush Sports (in Texas, I think). It uses a Wilson Combat style barrel nut, and is modeled after their 'Trim' model hand guard. I'm going to put it on my grandson's AR if I tear his up. The only kicker is that it takes a 1-3/16" crow foot wrench to torque it on, and they are hard to find, locally.

    https://rouschsports.com/shop/ar15-upper-parts/ar15-handguards-forends-quad-rails-best-dicount-price/uls-keymod-free-float-handguard-forend-7-9-10-12-15-inch/
  • snake284snake284 Senior Member Posts: 22,394 Senior Member
    bisley wrote: »
    What is the point of buying a 'lego' rifle if you can't replace the parts on it, yourself? I'm asking for advice from someone who may have already solved this 'plumbing' problem. I'll solve it myself, if necessary - I'm just trying to reduce the pain of this learning experience, as much as possible. :jester:


    The barrel nut below is similar to what I have, in that it has the jam nut that threads onto the hand guard and is tightened to secure the hand guard, but different in that I think there must be no threading on the muzzle end. The one shown here is for a screw-on full diameter quad rail, whereas my rail is a small diameter with a channel for the gas tube/block which eliminates the possibility of the hand guard being spun on. It is simply secured by the jam nut and a tight fit on the sleeve that it slides over, plus one hex screw at the bottom that clamps the handguard to the sleeve to hold it in place while the jam nut is tightened.
    AM-66-FF-NR_1-450x300.jpg

    The hand guard below installs similar to mine, except mine is a narrow diameter that doesn't spin on over the gas tube/block.

    ar-15-quad-rail-handguard-165-inch-free-float-black-540.jpg

    Yeah, I see your point. But I think what Dan is thinking is like what I'm thinking. You're in a learning mode on the AR as I would be. To me, the smart thing would be take it to a specialist and learn. Then next time you will know. Now! Got that off my chest.... hehehe, oh but I'm so good at advice, and SO BLUMMING STUPID about not following my own! You aint' got that thing chucked up in the vice yet with a two pound hammer in your hand?

    :rotflmao::rotflmao::rotflmao::rotflmao::rotflmao::rotflmao::rotflmao::rotflmao::rotflmao::rotflmao:
    Daddy, what's an enabler?
    Son that's somebody with nothing to do with his time but keep me in trouble with mom.
  • bisleybisley Senior Member Posts: 10,798 Senior Member
    OK, this saga is over. I had to ruin 3 rail screws and skinned some paint up, but it's off, and intact, otherwise. The hand guard was threaded and screwed onto the barrel nut, which was so loose that I didn't need a wrench to take it off. After I filed a slot into the hex screws and got the rail off, I was able to get to the set screws on the gas block and tap it off. Then, I just spun the hand guard off. This hand guard was intended for a barrel with a rifle length gas port - not a carbine - length. They apparently were able to slide the gas block on underneath it and get it lined up and stabbed through the hole. It wouldn't piss me off too much, except they didn't torque the barrel nut.

    Farm Boy, I installed the Rousch hand guard and I like it OK. It takes a little diddling with the barrel nut and shims to get everything lined up for the hand guard screw holes, and the hex screws that secure the guard have metric heads, but they did send a wrench with it. The top rail is T-marked and lines up fine. I've got no complaints, and will probably order another one in 15" for this rifle and use this 12" on my budget AR. It has a quad rail that I don't like - my grandson calls it a cheese grater, and the name fits.
  • JayJay Senior Member Posts: 3,858 Senior Member
    Pretty much what I was thinking. Glad you got it apart. It's pretty common to put a rifle length handguard on a carbine length barrel using a low profile gas block. Did one for a friend a few years ago like that. 14.5" barrel, rifle length handguard, LP gas block. Bout the only thing that sticks our of the handguard tube is the flash hider. That's what he wanted....

    Anyway, glad you were able to get it without too much more trouble...
  • bisleybisley Senior Member Posts: 10,798 Senior Member
    This hand guard has a 1.3" inside diameter, and it didn't look possible to install the gas block underneath the hand guard. Now that I've seen it, I could do it, but I don't think I would ever want to.
  • JayJay Senior Member Posts: 3,858 Senior Member
    I have to wonder why they left the barrel nut so loose. A guy doesn't just forget to torque the barrel nut and just happens to get lucky and have the gas tube line up. My guess is, they tightened it, then backed it off to line up the gas tube or tightened it just enough to where the gas tube lined up and called it good. After everything settled in and got moved around during use, it came loose. That's why I always tighten to 35 ft lbs, then tighten till the gas tube lines up.
  • bisleybisley Senior Member Posts: 10,798 Senior Member
    I tightened to 35 lbs, then set the wrench on 50 lbs. and tried to tighten till the holes lined up, before hitting 50. They still didn't line up, so I backed off and added a shim, then repeated. I ended up with three shims and somewhere just a little past 35 lbs. of torque.
  • Farm Boy DeuceFarm Boy Deuce Senior Member Posts: 6,083 Senior Member
    The Roush hand guards look like they go on just like the ALG hand guard I have on my HD carbine. You are correct in saying that it takes a little time to get just right.

    You got a Friday upper or maybe Monday upper. Glad you got it fixed.
    I am afraid we forget sometime that the basic and simple things brings us the most pleasure.
    Dad 5-31-13
  • Diver43Diver43 Senior Member Posts: 10,903 Senior Member
    Glad to hear it worked out for you with too much hassle.

    I do not get why things were so loose though
    Logistics cannot win a war, but its absence or inadequacy can cause defeat. FM100-5
  • bisleybisley Senior Member Posts: 10,798 Senior Member
    Hey, farm boy,

    Here is what a cheapie AR build looks like with the hand guard you were looking at. I kept the 12" Rousch for my Palmetto lower kit and complete upper. I took a picture of the 15" that I put on my grandson's, but Photobucket 'gilflirted' on me and I don't have time to mess with it, right now. I'll post it later if you want to see it. It's a pretty good setup for the price - very solid and not too hard to install. The rails matched perfectly on mine, once I got the barrel nut just right - something under 60lbs of torque for mine.

    Of course, I blew the budget part of the deal, when I added the Leupold shotgun scope and Burris PEPR QD mount.

    20160205_103706%20640x240.jpg
  • Farm Boy DeuceFarm Boy Deuce Senior Member Posts: 6,083 Senior Member
    That looks good.
    I am afraid we forget sometime that the basic and simple things brings us the most pleasure.
    Dad 5-31-13
  • bisleybisley Senior Member Posts: 10,798 Senior Member
    I honestly don't know what makes a $200 name brand better than this, unless it might be ease of installation, but this one is not that hard...if you have the crowfoot for torquing the barrel nut. I may find out down the road, but for now, cheap is good. The 15" looks good, too.
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