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Thread: Phosphate under gas block

  1. #81
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    Quote Originally Posted by lamarbrog View Post
    ... I hate to argue with someone with credentials such as yourself on technical matters... but staking is there in the event that over time the screws wiggle loose. Staking is not to tighten the screws.
    The military standard is that the stakes should not distort the side surfaces, and they should result in a removal torque no less than 55 and no more than 100 inch-lbs. So the goal of staking is not to keep the screw from moving, but rather to keep it from removing with less than 55 inch lbs of torque. And if it takes more than 100 inch lbs, then the staking was too much.

  2. #82
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    dupelicat post
    Last edited by rsilvers; 12-08-11 at 00:13.

  3. #83
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    Quote Originally Posted by lamarbrog View Post
    Okay... I still don't trust Bushmaster for such a critical part. If you wouldn't change it... don't. Personally, I would.
    They are making good bolts.

  4. #84
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    Quote Originally Posted by rsilvers View Post
    The military standard is that the stakes should not distort the side surfaces, and they should result in a removal torque no less than 55 and no more than 100 inch-lbs. So the goal of staking is not to keep the screw from moving, but rather to keep it from removing with less than 55 inch lbs of torque. And if it takes more than 100 inch lbs, then the staking was too much.
    Mmm... I haven't brushed up on the specs in a while, and don't care to look them up tonight.

    My understanding is that the screws should be torqued to about 55 inch lbs... So, assuming they went over a bit, 55 inch lbs exactly wouldn't remove them... staking or no staking.

    The staking is there to save your butt if the get loose from some reason over time, or were not torqued properly to begin with. Properly torqued gas key fasteners, in a perfect world, would not need staking at all. Staking is a backup.

  5. #85
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    Quote Originally Posted by rsilvers View Post
    They are making good bolts.
    Alrighty then... If I ever have a Bushmaster, I'll trade you my bolt for a BCM. Then we can both be happy.

  6. #86
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    Quote Originally Posted by lamarbrog View Post
    Properly torqued gas key fasteners, in a perfect world, would not need staking at all. Staking is a backup.
    Agreed, but once staked, the screws should be removable with between 55 and 100 inch lbs of torque.

  7. #87
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    Quote Originally Posted by rsilvers View Post
    Agreed, but once staked, the screws should be removable with between 55 and 100 inch lbs of torque.
    We are in agreement, then.

  8. #88
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    Quote Originally Posted by lamarbrog View Post
    Gold/Five Coil.

    Black insert, and possibly a Crane O-ring.
    I never felt comfortable referring to spring by the number of coils when the drawing says that the number of coils is a REF and it changes from batch to batch.

    I ran spring analysis software on pretty much all extractor springs in the Brownell's catalog. The newer military gold one was not bad but still over-stressed (over 45% of MTS). There are some absolutely horrifyingly bad extractor spring designs in some of 'your' favorite bolts (I don't mean you specifically, lamarbrog). Some were at 80% of MTS.

    I was not able to buy the spring that I wanted in the AAC bolt - had to have it made. Basically, the AAC spring is the original M16 spring design (which is not overstressed). Except I had them made from MountJoy brand Rocket Wire to make it even lower % of MTS, and then the extraction force was raised to carbine standards without adding additional stress to the spring by the o-ring.

    I pull all other springs out of bolts, including the newer gold military ones.

  9. #89
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    Quote Originally Posted by lamarbrog View Post
    Alrighty then... If I ever have a Bushmaster, I'll trade you my bolt for a BCM. Then we can both be happy.
    I wish there was a way for you to CMM them both, but those machines are $75K.

  10. #90
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    Quote Originally Posted by rsilvers View Post
    I never felt comfortable referring to spring by the number of coils when the drawing says that the number of coils is a REF and it changes from batch to batch.

    I ran spring analysis software on pretty much all extractor springs in the Brownell's catalog. The newer military gold one was not bad but still over-stressed (over 45% of MTS). There are some absolutely horrifyingly bad extractor spring designs in some of 'your' favorite bolts (I don't mean you specifically, lamarbrog). Some were at 80% of MTS.

    I was not able to buy the spring that I wanted in the AAC bolt - had to have it made. Basically, the AAC spring is the original M16 spring design (which is not overstressed). Except I had them made from MountJoy brand Rocket Wire to make it even lower % of MTS, and then the extraction force was raised to carbine standards without adding additional stress to the spring by the o-ring.

    I pull all other springs out of bolts, including the newer gold military ones.
    Could you explain this in a little simpler terms? Extractor springs are one of those things I am very interested in, but know fairly little about.

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