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Posted: 12/2/2015 1:13:48 PM EDT
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I have read on here from Dano that when the charging handle is pulled to the rear the bolt face should be 1/8" or 1/4" in front of the rear ejection port window. My build the bolt face is flush with the rear of the ejection window. Now I recall after reading about this I went and checked the one I built and it was in front of the ejection window. Now when I check it is flush. Has only been 500 or less rounds between the checks.
What would cause the change? Is there are potential concern of the bolt face being flush with the window? I have little over 700 total rounds through it with no malfunctions. |
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Quoted:
I have read on here from Dano that when the charging handle is pulled to the rear the bolt face should be 1/8" or 1/4" in front of the rear ejection port window. My build the bolt face is flush with the rear of the ejection window. Now I recall after reading about this I went and checked the one I built and it was in front of the ejection window. Now when I check it is flush. Has only been 500 or less rounds between the checks. What would cause the change? Is there are potential concern of the bolt face being flush with the window? I have little over 700 total rounds through it with no malfunctions. Compression of the buffer bumper would be the best guess, unless the tube is made out of cheap material that allowed either the tube to strech, or the bottom void of the tube to peen instead. The quick way to solve the problem if the build has a carbine receiver extension, face the front of the tube so the tube can be threaded in one more wind and kiss the center post of the buffer retainer. Hence the bottom of the tube is longer than the top section, so it just the bottom lip of the tube that just needs to be faced back a touch. Since the tube is threaded 18tpi, it means that for every wind of the tube, is going to move forward .056". So if you measure the gap now from the end of the tube to the face of the buffer retaining center pin, subtract that by the .056", tells you now much you need to face the end of the tube back to thread the tube in another wide, and have the end of the tube correctly kiss the post on the buffer retainer. If you have a standard receiver extension, then it will be the face of the seating lip surface that will need to be set back via a lathe instead. If you want to go the faster way without having to do any math of just how much of the front of the tube needs to be faced back for a carbine receiver extension, then notch the bottom of the tube with a small round jewelers file to allow you to spin in in another wind isntead. 
And the reason that we don't want the face of the bolt to be even or behind the ejection port, we want the spent case to clear the back ejection port edge when its pivoted off the face of the bolt at the back of stroke when you have a dead blow effect buffer in play that will stall the B/C at the back of stroke instead. Hence if the spent case is tagging the back of ejection port window on the way out, only a matter of time until a spent case ends up being deflected right back into the action to end up with a stove pipe jam isntead. |
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Quoted:
Dano, the bottom lip of the buffer tube is slightly touching the retaining pin. So if you face the bottom lip .056" back, this will allow you to spin the tube in one more wind, which beings the back void of the tube .056 forward as well, and limits the B/C more forward against the ejection port window forward. Hence the glitch, the void depth of the tube is slightly too deep to begin with. |
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Quoted:
So if you face the bottom lip .056" back, this will allow you to spin the tube in one more wind, which beings the back void of the tube .056 forward as well, and limits the B/C more forward against the ejection port window forward. Hence the glitch, the void depth of the tube is slightly too deep to begin with. Quoted:
Quoted:
Dano, the bottom lip of the buffer tube is slightly touching the retaining pin. So if you face the bottom lip .056" back, this will allow you to spin the tube in one more wind, which beings the back void of the tube .056 forward as well, and limits the B/C more forward against the ejection port window forward. Hence the glitch, the void depth of the tube is slightly too deep to begin with. Just use files to face the tube? |
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Mill is faster, but you can use a file if push comes to shove to do it by hand.
Just use a caliper to scribe index line to give you an idea of how far back you need to face the end of the tube, and do a couple of dry fittings along the way with the buffer retainer pin in place. |
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Quoted:
Mill is faster, but you can use a file if push comes to shove to do it by hand. Just use a caliper to scribe index line to give you an idea of how far back you need to face the end of the tube, and do a couple of dry fittings along the way with the buffer retainer pin in place. So agree that a mill be faster, but I don't have access to one. It's hand files or dremel. Good tip on the scribe line. |
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