AR-15 Screws Stuck - How to Remove

ZigZagZeke

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I have been using my Bushmaster with the scope the way it came originally, but after a few outings I noticed that the sight plane was just too high for me. I noticed that the scope mounts are sitting on a pair of risers that could be removed to make the scope sit about 3/8" lower, which would be perfect for my desired sight plane. The problem is that the 2.5 mm allen head screws holding the risers on are so tight that I can't break them loose. I've applied all the torque I can without stripping the screw heads or twisting off the allen wrench and they still won't budge. Does anybody have a suggestion on how to remove them before I give up and drill them out?

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Perhaps they were installed with permanent lock-tite, if so heating them with a propane torch will cause the thread-locking compound to burn off. Of course you must be careful not to melt anything, heh heh Just Joking, it really takes a lot to melt a gun with a propane torch!
Seems like most allen head screws are grade 5 to 8, which makes for some tough drilling...Those mounts can be easily cut off if they can be replaced.
 
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Have you tried a penetrating oil, like PB Blaster? Spray on, wipe off any excess, and allow to soak in for several hours before attempting to remove the bolts.
NOTE...these are fairly potent concoctions...not sure how they would react with the finish on your upper receiver.
You could also try heat...apply a hair dryer for a few minutes and then hit it with the wrench.
HIH,
John
 
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propane torch, as suggested... this is common, and i find myself torching red loctite several times a month. just turn it on low heat so the little blue jet is about 5/8" long, and stick that little blue jet right on the steel needing to be heated- in this case, get the thread end- NOT the head end- hot... hold the jet on the ends of the screws for about 30 seconds, then try to loosen. repeat as necessary, if'n they don't come right off. you won't hurt anything with the heat that low.
 
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ZigZagZeke

ZigZagZeke

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Have you tried a penetrating oil, like PB Blaster? Spray on, wipe off any excess, and allow to soak in for several hours before attempting to remove the bolts.
NOTE...these are fairly potent concoctions...not sure how they would react with the finish on your upper receiver.
You could also try heat...apply a hair dryer for a few minutes and then hit it with the wrench.
HIH,
John
You just jogged my memory. I have a heat shrink gun that gets considerably hotter than a hair dryer, but not hot enough to damage aluminum or the finish. I think I'll try that before escalating to the propane torch. If none of that works, I'll probably end up cutting the mounts down the middle and they should just fall off.
 

ron

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I had a stuck screw on a front sight base of an AR. By all means you should try the heat gun. It did not work for me. Had to use map gas from a small torch. Worked great and the barrel was not harmed it shoots great. Good Luck
 
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You just jogged my memory. I have a heat shrink gun that gets considerably hotter than a hair dryer, but not hot enough to damage aluminum or the finish. I think I'll try that before escalating to the propane torch. If none of that works, I'll probably end up cutting the mounts down the middle and they should just fall off.
unless your heat gun gets to 450, its not even going to help.. that's the temp loctite turns from thread locker to dust.
 
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Cutting the mounts down the middle will most likely not work. The bolt goes through the recess in the picatinni rail. The mount would still be tight to the upper receiver. Correct me if im wrong. I would go with the torch method. That is what several manufactures recommend doing when you thread lock things to get the undone.
 
Cutting the mounts down the middle will most likely not work. The bolt goes through the recess in the picatinni rail. The mount would still be tight to the upper receiver. Correct me if im wrong. I would go with the torch method. That is what several manufactures recommend doing when you thread lock things to get the undone.
You are correct. I would go with the torch before I started cutting or drilling. A little heat won't do anything to the rifle, but a cutting wheel or a poorly lined drill bit can leave some nice gouges.
 
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I use a small pencil flame torch regularly for "Loctite" issues. The key to success is to keep the flame off the areas you don't want it to damage. A simple tip is to hold a washer with a hole just a little larger than the bolt/screw end in a "hemostat". This tool alows you to lock the washer in it's grip and maneuver it around easily.

Hold the washer close, but not touching, with the hole over the area to be heated. Direct the flame at the hole in the washer long enough to soften the loctite. The washer makes a nice heat shield for the surrounding area while getting plenty of heat through the hole.

Another tip for striped or about to strip allen heads. With a pick scrape the inside of the bolt head until you see rough, bare metal. Degrease with some acetone. Take NEW allen "L" shaped wrench and scrape the end clean with a knife. Degrease it too. Then J-B weld the wrench in the allen bolt head and let cure for full strength. When fully hardened then just remove the bolt and discard along with the wrench. Works a lot better than drilling if you want to save the part the bolt secures.
 

AMT

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If you are leary about applying a torch to your firearm try a soldering iron. Hold it in the hex head for a bit. The heat transters through the screw and should heat the loctite enough to soften it enough to back out with allen wrench. A lot of times I'm not in a position to apply a torch. The soldering iron has worked every time from me in my applications.
 
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ZigZagZeke

ZigZagZeke

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Using a propane torch I put as much heat as I am comfortable with on the screws last night and still no movement. So far the screw heads are not stripped, even though I've severely twisted a 2.5mm Snap-on allen wrench, so I'm hesitant to do anything that will destroy the heads until I've exhausted all other avenues. I'm OK with destroying these riser blocks. They can be replaced for about $20 for the pair.

The scope rings in question are high or extra high. Add in these 1/2" riser blocks and I've got nearly an inch clearance between the scope and the hand guard. Most Bushmasters I've seen with a 50mm scope have about 1/2" clearance, and 1/2" is way more comfortable and gives me a much more stable sight picture. I discovered this by remounting the scope directly to the receiver behind the riser blocks. If I could slide the scope and rings forward to the location where the riser blocks are the location and height would be perfect. Right now the scope is a little too close to my eye and it's all the way forward in the rings. I need to get rid of these risers without destroying anything. Anybody know of a good gunsmith on the east side who might want to tackle this job?
 
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you putting the heat on the head end or thread end? the threads are on the other side... blue jet, 30 seconds contact, and dont be afraid to twist hard.

i've completely twisted hex wrenches around, and even broken one or two off- so long as you have the right size and dont slip, you won't strip the head.
 
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ZigZagZeke

ZigZagZeke

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you putting the heat on the head end or thread end? the threads are on the other side... blue jet, 30 seconds contact, and dont be afraid to twist hard.

i've completely twisted hex wrenches around, and even broken one or two off- so long as you have the right size and dont slip, you won't strip the head.
Yep, I was heating the thread ends, but the aluminum transfers heat pretty fast and I'm leery of getting the receiver too hot.
 
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Yep, I was heating the thread ends, but the aluminum transfers heat pretty fast and I'm leery of getting the receiver too hot.
aluminum dissipates heat well, it actually conveys it poorly. you can get one spot red hot while holding it in another- which i just did not 40 minutes ago in my own shop.

sounds like you're not getting it hot enough.
 
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welding shops sell a material that is like silly putty that could help keep the upper from pulling away your heat. it will also protect your finish from the flames if you use it to surround the thread area. micro butane torches work the best but a small flame on a map gas torch will work well too.

you can use Kroil, pb blaster, or just about any other penetrant (MOPAR penetrant with graphite is the best in my opinion) after it has been heated then allow it to cool and sit for a half hour, the heat will pull in the penetrant and allow it to work into the threads.

low heat will usually soften locktite and allow it to be worked loose but it sounds like either dissimilar metals have caused corrosion or the threads have been ruined from over tightening. Do the threads protrude out of the hole on the other side and if so are they ok?
 

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