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Thread: Extractor Snap-Over Timing?

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    Extractor Snap-Over Timing?

    While reading something on fwd. assists (which I am not a fan of) I did begin to wonder at what point the extractor would snap over the rim of the feeding cartridge, versus the bolt merely shoving an unsecured round ahead of it. Until the extractor engages the rim the round is somewhat uncontrolled.

    Seems to me that extractor engagement would not occur until the round chambers, is stopped by the case shoulder, and the bolt lugs are beginning to rotate into locked position.

    If so, then before that time a pull to the rear with the charging handle wouldn't extract that round--correct?

    Lots of hypotheticals here, and I also need to dig out the manuals.

    Comments?

    Thanks.

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    Quote Originally Posted by Bat Guano View Post

    If so, then before that time a pull to the rear with the charging handle wouldn't extract that round--correct?
    you mean IF you needed to use the fwd assist, didn't and THEN wanted to extract? it's late for me

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    Quote Originally Posted by Bat Guano View Post
    While reading something on fwd. assists (which I am not a fan of) I did begin to wonder at what point the extractor would snap over the rim of the feeding cartridge, versus the bolt merely shoving an unsecured round ahead of it. Until the extractor engages the rim the round is somewhat uncontrolled.

    Seems to me that extractor engagement would not occur until the round chambers, is stopped by the case shoulder, and the bolt lugs are beginning to rotate into locked position.

    If so, then before that time a pull to the rear with the charging handle wouldn't extract that round--correct?

    Lots of hypotheticals here, and I also need to dig out the manuals.

    Comments?

    Thanks.
    Not sure where you're coming from on this....

    I believe you pretty much have it correct. The round is uncontrolled as it is stripped from the Mag., while it is driven by the top of the bolt from the Mag. into the chamber. Pretty much when the round meets with the resistance of the case shoulder contacting the respective part of the chamber, the extractor snaps over the case head.

    I don't know why you would try to engage the charging handle before or during this cycle. Once the cycle is completed, activating the charging handle would indeed eject the loaded round.

    I could be wrong, but I don't think so.

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    Quote Originally Posted by toddackerman View Post
    Not sure where you're coming from on this....

    I believe you pretty much have it correct. The round is uncontrolled as it is stripped from the Mag., while it is driven by the top of the bolt from the Mag. into the chamber. Pretty much when the round meets with the resistance of the case shoulder contacting the respective part of the chamber, the extractor snaps over the case head.

    I don't know why you would try to engage the charging handle before or during this cycle. Once the cycle is completed, activating the charging handle would indeed eject the loaded round.

    I could be wrong, but I don't think so.
    I think he's asking that if the bolt does not fully seat (requiring a FA tap) will using the charging handle extract and eject the round, or leave it partially inserted in the chamber.

    At least that's the gist I got.

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    The AR15/M16 is essentially a push feed mechanism. Rounds being stripped from the magazine are pushed ahead of the bolt, sitting in front of the lower lugs and sliding up the bolt face. The extractor being spring loaded does not clip over the rim of the case until the case is aligned with the case head recess and the case stops with sufficient force that the extractor is forced open by the angle that sits on the front edge of the extractor lip.

    While this sounds very hit and miss it is one of the more carefully thought out parts of the mechanism and one that is very easy to screw up. Correct magazines hold the base of the case, allowing it to slide forward and do not release the round into free space until the nose of the cartridge is in the chamber. At this point the base is released but the round is still controlled as it cannot now move in any direction except to chamber. At this stage the round is still being pushed and the extractor is not yet engaged.

    You will note how important the magazine is in this operation. It only takes a slight shift in specifications of the radius at the top of the magazine or the mag lip length to make this action unreliable.

    As to the forward assist, you should learn to love this item. The forward assist is not as popularly discussed used to force rounds into the chamber, but rather should form part of your SOP every time you handle the weapon. On loading the rifle, you will note that there is no loaded chamber indicator. A partial extract will verify the presence of a round in the chamber either by a visual or tactile cue. Dropping the bolt from this position is not a sure way of ensuring that the gun is in battery so the forward assist is tapped to make sure. Partial extractions are required for all over the surf use and water drainage and arctic conditions require that the bolt is moved partially and the round is moved every 20 to 30 minutes. In all cases the forward assist is the check that the gun is in battery. While the "new" fashions in tactical teaching often miss this feature or bypass it with suggestions such as noting which side of the mag is loaded then removing the mag to see if the round is stripped, or pushing the bolt with the gas pocket using your thumb, unseating the magazine brings the gun back to an unknown condition. As to pushing the bolt with your thumb you do not want to touch anything metal with flesh at -40F.

    Bill Alexander

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    Bill Alexander clarified it nicely--better than the references I consulted last night.

    The part about checking for a chambered round by partial retraction of the bolt and then ensuring closure and locking with the FA makes excellent sense, as I have always liked to be able to see "brass" when checking a 1911.

    The M1 and M14 have essentially the same extractor/ejector sytem and feeding characteristics, except that you can see into them better and there is a nice handle that you can push on, yank on, and stomp with a boot heel if necessary.

    BTW even as a card-carrying Luddite, I do have a FA--it came on the rifle.

    Thanks.

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    Quote Originally Posted by Bat Guano View Post
    Bill Alexander clarified it nicely--better than the references I consulted last night.

    The part about checking for a chambered round by partial retraction of the bolt and then ensuring closure and locking with the FA makes excellent sense, as I have always liked to be able to see "brass" when checking a 1911.

    The M1 and M14 have essentially the same extractor/ejector sytem and feeding characteristics, except that you can see into them better and there is a nice handle that you can push on, yank on, and stomp with a boot heel if necessary.

    BTW even as a card-carrying Luddite, I do have a FA--it came on the rifle.

    Thanks.
    While I think Bill has (as always) made some excellent points, I tend to agree with those who believe there is way to much "Chamber Checking" occurring. Once you have charged your weapon, and have confirmed it is in battery, and the top round has been stripped into the chamber...replace the Mag. with a "Push/ Pull", and leave it alone. You should not have to remind yourself of the condition of the weapon IF you have engaged the safety. If the Safety is on...the weapon is GTG.

    Clint Smith has said..."The Charging Handle, and Forward Assist are not your friends, and the less you use them...the better". (Paraphrase)

    I tend to agree. Every time you operate the charging handle (with a load in the chamber), you take the round out of battery, and chance that it won't return to battery. With a properly maintained and lubed rifle, it WILL go into battery 100% of the time from a Bolt Open condition either by hitting the Bolt Catch, or by "sling shotting" the charging handle...which is one of the fragile parts of the system, and they do break.

    Regarding Forward Assists...I've never had to use one after ~7,000 rounds on my current MRP upper. Again, I think proper maintenance is key here.

    As always, I respect others opinions and YMMV.

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    Quote Originally Posted by toddackerman View Post
    While I think Bill has (as always) made some excellent points, I tend to agree with those who believe there is way to much "Chamber Checking" occurring. Once you have charged your weapon, and have confirmed it is in battery, and the top round has been stripped into the chamber...replace the Mag. with a "Push/ Pull", and leave it alone. You should not have to remind yourself of the condition of the weapon IF you have engaged the safety. If the Safety is on...the weapon is GTG.

    Clint Smith has said..."The Charging Handle, and Forward Assist are not your friends, and the less you use them...the better". (Paraphrase)

    I tend to agree. Every time you operate the charging handle (with a load in the chamber), you take the round out of battery, and chance that it won't return to battery. With a properly maintained and lubed rifle, it WILL go into battery 100% of the time from a Bolt Open condition either by hitting the Bolt Catch, or by "sling shotting" the charging handle...which is one of the fragile parts of the system, and they do break.

    Regarding Forward Assists...I've never had to use one after ~7,000 rounds on my current MRP upper. Again, I think proper maintenance is key here.

    As always, I respect others opinions and YMMV.
    I like Clint Smith and in most cases I perform administrative loading proceedures as he does ie, using my weak hand middle finger to verify bolt closed.

    But I think if you re-read Bill Alexanders post you'll see he was speaking of extream conditions. I can atest that in Artic conditions you'll want to move the BCG and chambered round on a regular basis to verify weapon is not froze. At times I will move the BCG far enough back to bump the hammer. A visual cue such as relation of port spring to bolt carrier when you have gone far enough back, however you should learn to feel when you have gone far enough incase your in the dark. This is especially important when -20 and COLDER and moving from heated to cold environment. You'll be doing this with gloves on and thats when you FA will be your friend.

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    I am pretty sleepy, but here, watch this. It will show you first-hand what happens when you fire the weapon.

    http://smg.photobucket.com/albums/v4...sppedfguns.flv

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    Quote Originally Posted by WS6 View Post
    I am pretty sleepy, but here, watch this. It will show you first-hand what happens when you fire the weapon.

    http://smg.photobucket.com/albums/v4...sppedfguns.flv
    Cool Vid!

    Nothing like a little Madonna mixed in with M-16 and M9 operation.

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