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Thread: Gas block stuck

  1. #11
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    After this experience I don't think I'll be changing the gb again anytime soon. And now I know how to build an upper, which is a good thing for me, but probably a bad thing for my bank account in the long run .

    I've found some tips on here about assembling low pro gas blocks & I think I'll set the gb with blue loctite and take it to the range. If the bolt locks back and the outside of barrel is free of black streaks I'll reassemble the screws with red loctite.

    There are several types of red loctite, so I'm assuming this was assembled with the common red loctite and I'm just a poor machinist/gunsmith - which is the most likely case. There are very permanant loctites meant for pins, etc that are basically indestructible. I ordered the complete upper from BCM with the old rail on it. ?
    Just because you're necessary doesn't mean you're important.

  2. #12
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    So this is proof that set sccrews are an adequate way time install a gas block.

  3. #13
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    I use a MAP torch for a few minutes.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

  4. #14
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    BCM uses high temp red Loc-tite on their gas blocks. In addition the screws are a special type that have scallops on the bottom so they lock into the dimple that is drilled.



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  5. #15
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    Quote Originally Posted by Merle View Post
    So this is proof that set sccrews are an adequate way time install a gas block.
    Affirmative.

    Update: m I got a new gas block & tube and installed them tonight. It took me about an hour to completely assemble my upper and install my new larue rail. I am a little worried that it was a pretty easy operation, but I triple torqued the barrel nut to 40 ft-lbs and everything else was pretty straight forward.
    Why don't people build more of these things!?!? It's really easy. I also mounted my xps2-2.

    I have to say, that now that I have a rail that I can actually wrap my hand around, I understand the costa grip.

    Unfortunately, my crush washer is toast now- my flash hider is about 20 deg. Short of where it should be and won't go any farther. I guess I can bench shoot like that, right?
    It's also a good excuse to buy a battlecomp... Anyone have them on sale right now???
    Attachment 13629
    Just because you're necessary doesn't mean you're important.

  6. #16
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    Update:
    Just got back from the range. The rifle failed to lock back a few times. Also it would feed correctly slow firing, but when rapid firing it would tend to not feed. It would eject, but the bolt would miss the round in the mag and jam halfway closed with the case dented. I could reset it with the charging handle and would be gtg.

    Am I correct in guessing that my gas block might be mis-aligned? However, my barrel has a dimple opposite the gb hole, so shouldn't that make the FB self align?

    I'm shooting x-tac 62 gr greentips, so the ammo shouldn't be the issue.


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    Last edited by Krusty783; 09-29-12 at 17:27.
    Just because you're necessary doesn't mean you're important.

  7. #17
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    Well, there's residue all over the barrel and rail, so I know my gb is not correctly aligned.

    I traded for my complete lower before I knew what I know today & I've been using the buffer and spring that were in it. I got a kitchen scale and weighed the buffer. Apparently I have a carbine buffer that's on the light end of the range. I'd say this explains why the gun would cycle at all with a misaligned gas block. Time for a h or h2 buffer and a new spring would probably be a good idea also.


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    Just because you're necessary doesn't mean you're important.

  8. #18
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    My BCM Block is Stuck!!

    Well I wish I would have read this thread this AM. It seems like everytime I attempt to do something that involves gunsmithing I strip bolts or set screws.

    I was removing my BCM gas block so I could remove my DD Lite Rail and install a new rail and neglected to heat up the gas block. The front set screw came out with only a little hassle but the second is ****ed. The head is stripped and I can't get the little bastard out. I guess I better let someone with more experience with these things get it off or I will end up damaging my new BCM SS barrel.

    I wonder if I will have to buy a new gas block if so that was a dumb move that cost me 45 bucks.
    Tzoid

    Texan raised in " The Peoples Republic of Maryland"

    "RRA- if they came with a blow job I wouldn't take one." - Pat Rogers

  9. #19
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    Based on my experience, you might as well order a new gas block tonight. I have a YHM low profile one now and its fine.

    Here's some advice based on my mistake:
    -The Red loctite they used is permanent and you probably aren't equipped to remove it, short of putting the barrel in an oven at 550 for a few hours. I used a whole propane can torch trying to melt the loctite and got nothing for my effort. The barrel has a lot of steel and it soaks up a lot of heat. So you need to stick it in an oven for a few hours or use an acetylene torch to get it really hot.

    But, you rounded out the screw, so you almost have to drill it out now. You could heat it and try one of those remover bits, but those things never work for me.

    -You could take it to a gunsmith to drill out the set screw and replace the gb, or you can do it yourself if you're handy. A drill press is helpful, but you can do it by hand, here's how:

    -Take a small drill bit, about 1/8", and drop it in the empty hole. Wrap some tape around the drill bit to mark the depth of the hole to the surface of the gas block, and then use that to start drilling out the set screw.

    (Note: You should have a couple spare drill bits of each size because if they're just the normal consumer bits, you'll probably wear at least one out, esp. if you're doing this by hand because you'll end up work hardening the steel if you let up on the pressure when you're drilling.-You let up and the steel & bit get hot but don't cut and this makes the steel harder and dulls the bit, which makes the problem worse.)

    -When you get to or near the tape on the first bit, switch to the next larger size and open up the hole. Remember: this screw is set into a dimple drilled into the barrel, so you can drill to the same depth as the first hole (relative to the gas block) and not hit the barrel. It only took me 2 bit changes to get the screw out. The 3rd/last drill should be about 3/16", I think. It should be large enough to totally remove the threads on the gb [and the loctite with them].

    -Here's the important part: When you start getting close to full depth on the last bit, be careful or you'll blow right thru the screw into the barrel and not get any indication (first hand knowledge ). Grab the gb with some vice grips that are really locked onto it and try to twist it around the barrel. If it won't budge, drill a little more and try again. When you get the threads basically gone, the gas block will break loose and you can wiggle it around and remove it.

    You might bend the gas tube, but those are cheap.

    Just take it somewhere if you aren't very mechanically inclined, or don't have the spare $ to buy another barrel if you duff it up. Just know it will probably be at least $100 for someone to touch it.

    When/if you install a new GB, it really helps if you have a shim to offset it from the shoulder on the barrel. The gap is a place for the handguard cap and it's about .060". I tried to free-hand it and missed the hole and my rifle was failing to feed about 25% of the time and the action wouldn't lock back on the last round. I took my rail off and found soot all over the barrel from the gas that missed the hole. So, I bought a std handguard cap on the internet for about $3 and cut it in half with tin snips to make a shim. I used that to reset the gb and it worked. I can send you a half of the cap if you want it.

    ++ So far, my only complaint with BCM is this adamantium-kryptonite blend loctite they use on the gas block set screws.

    Disclaimer: I am not a gunsmith, nor have I spent the night at a Holiday Inn Express lately. This is merely advice from an AR owner who's been in your shoes. If you hurt yourself, or your weapon you have my condolences.

  10. #20
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    I just ordered a new VLTOR Gas Block and my buddy who knows what he's doing will handle getting the last set screw out of the BCM Gas Block. If the BCM gas block is not totally shot I will ask them to send me two set screws and use it later. If it's worthless that's on me and the shitty soft set screws BCM uses in their GAS Blocks. I guess gas blocks of this type are single use and not built to be taken off.
    Tzoid

    Texan raised in " The Peoples Republic of Maryland"

    "RRA- if they came with a blow job I wouldn't take one." - Pat Rogers

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