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Thread: Cracked FSB, weld it?

  1. #11
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    Yes, the rail is a 13.8" troy so both holes will be covered. What would be the best way to go about pinning a low profile block? I have seen the jigs used for dimpling the barells for set screws, but have not seen anything like that for actually drilling for a pin. Also, with the factory pin holes exposed to the weather, would they possibly start to rust? Should I coat them with something?

  2. #12
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    Quote Originally Posted by mhanna91 View Post
    Yes, the rail is a 13.8" troy so both holes will be covered. What would be the best way to go about pinning a low profile block? I have seen the jigs used for dimpling the barells for set screws, but have not seen anything like that for actually drilling for a pin. Also, with the factory pin holes exposed to the weather, would they possibly start to rust? Should I coat them with something?
    That one company that makes a jig for dimpling also makes one for drilling pin for VLTOR and similar gas blocks.

    I don't use one of those. I use a milling machine and mill a flat spot on one side of the gas block (barrel is already mounted in the gas block) and then drill a 7/64" hole through both at the same time and then change drills and drill a 1/8" hole though both. If using sharp drills you should be able to use a straight pin or ream the hole with a taper pin reamer and use a taper pin. Both work excellently.

    If you're worried about rust in the holes on the barrel you can use RIG (rust inhibiting grease) on the barrel and holes. It works very well for this application. I sometimes use it on my own parkerized barrels where they'll be covered by a rail. I rub a thick coat of it on and rub it into the finish well. Then wipe off the excess. It'll smoke a lot the first time you get it really hot but it'll still protect against rust etc. It sort of creates a waxy barrier.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

  3. #13
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    Send the bbl and low pro gb to Steve at adco. Tell him to repark your bbl then PIN your gb on. Robb may also be able to offer this service, however I don't believe he can repark (he used norells last I knew).
    Acta Non Verba

  4. #14
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    I personally would just dimple and use a good setscrew GB - if it's under the rail, I wouldn't worry about pinning. IMO pinning is only essential with an exposed GB or FSB.
    Ken in Illinois

  5. #15
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    Unless I am mistaken, I dont think that my barell will need to be re-parked. Stupid me did not even think to check out Adco, they will pin a lo-pro block for $45. Thats not too bad of a deal. I dont have a mill, and the jig will probably cost about the same as what it would cost to have Adco do it, so I may go with them. Since they only put one pin in, would it be worthwhile to have them dimple my barell and put two set-screws in as well? This service is only $10, I figure the stronger the better, right?

  6. #16
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    One pin is plenty... no point in dimples and screws. Set screws are inferior when compared to a pin. If your bbl was parked under the fsb, you won't have to repark. If it wasn't, is repark where the fsb was as the new gb likely won't cover the fsb marks. I do believe BCM parks under fsb.
    Acta Non Verba

  7. #17
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    You are correct, my barell is parked under the FSB. I figured that one pin would probably do it, but I was not sure. I am new to all of this.

  8. #18
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    Got an E-mail back from BCM. I guess this is what I will be doing. They were very helpful! Gives me some piece of mind that this advice came from the factory.

    Hi Mark,
    Got the pics, thanks!
    Yes, I can see the crack.

    I am going to guess, even if left as is - that gas block is going to be very
    solid. When you remove it, it won't be easy.

    I would recommend replacing with a low profile gas block and retaining
    screws. If installed correctly, and a extended rail covering it from
    impact, they are not coming out. When we remove front sights, it takes
    about 2 minutes. When we remove our low profile gas blocks it takes about
    20 min with MAP gas to get it free. The set screw is set into the dimple
    and secured with loc-tite. It's a pain to remove.

    Otherwise look at the DD clamp on low pro gas block. Those work as well.

  9. #19
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    Awesome, BCM customer service at its finest.

    Quote Originally Posted by mhanna91 View Post
    Got an E-mail back from BCM. I guess this is what I will be doing. They were very helpful! Gives me some piece of mind that this advice came from the factory.

    Hi Mark,
    Got the pics, thanks!
    Yes, I can see the crack.

    I am going to guess, even if left as is - that gas block is going to be very
    solid. When you remove it, it won't be easy.

    I would recommend replacing with a low profile gas block and retaining
    screws. If installed correctly, and a extended rail covering it from
    impact, they are not coming out. When we remove front sights, it takes
    about 2 minutes. When we remove our low profile gas blocks it takes about
    20 min with MAP gas to get it free. The set screw is set into the dimple
    and secured with loc-tite. It's a pain to remove.

    Otherwise look at the DD clamp on low pro gas block. Those work as well.

  10. #20
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    http://www.bravocompanyusa.com/Danie...-p/dd-9111.htm

    What is everyone's thoughts on these DD clamp on blocks? They cover up the holes left from the origional FSB, and BCM reccomended them in another email they sent me. Has anybody used one and know that they stay put?

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