Size of FSB and GB holes for pins
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Thread: Size of FSB and GB holes for pins

  1. #1
    Gunco Member draktheas's Avatar
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    Jun 2008
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    Default Size of FSB and GB holes for pins

    My romy barrel doesn't have the same pin locations for the FSB and GB that came off the AMD-65. They are about 1/16 of an inch off, so if I line up one of the holes the other shows about 1/16 past the cross pin cut in the barrel in the other hole. It looks like I am going to have to re-drill the barrel for at least one pin on both. Any advise on the best method to do this would be appreciated as well as what size to drill them. Should they be undersized from the pins and if so by how much? .002? These seemed tight enough to be a pressure fit, but I am not sure. Also, is there a good source for replacement pins for the FSB and GB?

    Thanks in advance,

  2. #2
    Gunco Maniac sjohnson's Avatar
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    Sep 2006
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    .001 undersize should be enough. If you don't have one, get a letter size drill set. You'll have enough selection to pick a size that will work.

    A reamer would be best after drilling to close undersize, but drill bits will get it done.

  3. #3
    Resident Evil s70fan's Avatar
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    Pins, reamers, drills and a few hundred thousand other things. A great source for things builders need.

    Welcome to the 21st century, things are going to be very different.

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  5. #4
    Happy Camper hcpookie's Avatar
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    I ordered 3mm x 12mm pins from McMaster and they work great as replacements. 3mm = .118. .1094 = 7/64 which works great for a pilot hole. Then follow up with a #32 bit - .116" - and you'll have a nice little hole to paly with. .002" undersize is REALLY tight, but that is compensated by the fact that a drill tends to drill more loosely than a reamer.

    Oh, one important tip - drill HALFWAY, flip over, then drill the other half! This keeps from breaking bits, *AND* give a straight hole. The times I got lazy and did not do that, the holes always turn out crooked because the hard metal of the barrel pushes the bit away.
    Gunco Member #10

    The "original" Boltcutter Rivet Squeezers:

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