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Thread: Do AR manufacturers "do" the mid-length differently?

  1. #31
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    IIRC the specified cyclic rate for an M4 carbine is between 700-900 cycles per minute. There's your operating parameters and I don't think anyone will disagree that a gun operating outside that range is more likely to have issues.

    Brass ejection may give you reason to suspect over-gassing but the only definitive way to tell if a gun is operating outside of cyclic rate specifications is to do cyclic rate testing with high speed photography or some other method. There is just no way to know how fast the carrier is moving by looking at the where the brass is going.
    Last edited by Eric D.; 09-30-12 at 23:07.
    B.A.S. Mechanical Engineering Technology

  2. #32
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    Quote Originally Posted by Eric D. View Post
    IIRC the specified cyclic rate for an M4 carbine is between 700-900 cycles per minute. There's your operating parameters and I don't think anyone will disagree that a gun operating outside that range is more likely to have issues.

    Brass ejection may give you reason to suspect over-gassing but the only definitive way to tell if a gun is operating outside of cyclic rate specifications is to do cyclic rate testing with high speed photography or some other method. There is just no way to know how fast the carrier is moving by looking at the where the brass is going.
    Yes and no.

    Exact speeds? You're right. Pull out the do-hickeys and do-dads.

    Behavioral wise though, experience shows us that, once again, with all things being equal (appropriate milspec parts, springs, etc, that are still well within their expected life cycle) that the gun will behave in certian manners that give a good indicator of bolt speed being either within spec, or outside of it.

    As has already been established, under "normal" circumstances, indicators of out of spec bolt speed are in fact caused by other aspects such as worn action springs, ejector springs, fouling, loose carrier keys, etc. Meaning that simple parts replacement removes those false indicators and all is well because the bolt speed was never actually out of spec.

    But, when all of those other factors are accounted for and the gun is still behaving in a certian manner, it does in fact mean that bolt speed (i.e. the cyclic rate as you mentioned) is out of spec and other issues need to be looked at. Gas port erosion, incorrectly machined chamber/throat or excessive gas port size (if on a brand new gun), etc.

    I fully understand that all brass throw does under normal circumstances is indicate that *something* is mimicing either excess or under gassing, but it's a hell of a lot easier to know which end of the spectrum to start troubleshooting from by paying attention to ejection. That's all i've been trying to say this entire time.
    Last edited by GrumpyM4; 10-01-12 at 00:34.
    It is missing the point to think that the martial art is solely in cutting a man down; it is in killing evil. It is in the strategem of killing the evil of one man and giving life to ten thousand -Yagyu Munemori

  3. #33
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    Say, what is the correct buffer weight for a BCM mid-length rifle?

  4. #34
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    Quote Originally Posted by rojocorsa View Post
    Say, what is the correct buffer weight for a BCM mid-length rifle?
    H buffer should run well. You may even be able to step up to an H2

  5. #35
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    Quote Originally Posted by Eric D. View Post
    IIRC the specified cyclic rate for an M4 carbine is between 700-900 cycles per minute. There's your operating parameters and I don't think anyone will disagree that a gun operating outside that range is more likely to have issues.

    Brass ejection may give you reason to suspect over-gassing but the only definitive way to tell if a gun is operating outside of cyclic rate specifications is to do cyclic rate testing with high speed photography or some other method. There is just no way to know how fast the carrier is moving by looking at the where the brass is going.
    This is exactly my point. Someone got to it before i could. I did not say IG said anything. I do not put words in other peoples mouth. I said if someone reputable like IG or grant says the chart is a good way to diagnose overgassing or bolt speed i Will take back everything i have said.

    If it is such a good way to diagnose a problem why would you be hesitant to tell people. Probably because you know it is bullshit. I think it is stupid to run something till it breaks, but it is just as stupid to think your 100% operational firearm has a problem based on this chart that just popped up in the last couple years. I agree that a system has an optimal functioning range, but without proper testing you have no clue if it was within parameters.

    Bottom line is there was no malfunctions (your claim), and you think it has a problem. It is obvious you believe yourself to be an SME. So regardless you Will continue to diagnose guns than run 100% to have some sort of problem.

  6. #36
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    I know my Noveske N4 isn't a TRUE middy, but FWIW I've never had an issue with it, and I shoot crap ammo almost exclusively. (Shout out for poor people!!!) Tons of Wolf, mainly.
    Gun and Gear Reviews- www.almosttacticalreviews.com

  7. #37
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    Personally, I don't put any faith in the ejection chart. If GrumpyM4 wants to, that's his prerogative.

    The reason I don't have any faith in it is based on my own experience with an SR15. This gun is known to be under gassed. Mine runs fine with good brass cased .223 ammo. I can tell a difference shooting it with 5.56 vs .223. With weaker ammo, the gun almost feels sluggish & recoil is very soft, but it runs fine. There is no way that gun is over gassed. The Chart tells us my gun should eject past 3:00. It actually ejects between 1 - 2:30, depending on ammo.

    I've talked to KAC in the past about it and they attribute this to how the shell hits the deflector. They actually test cyclic rate with slow motion film to determine proper port size, so I'm confident in the design of the barrel. My upper shows signs that the brass is actually hitting the front edge of the deflector and bouncing forward. Bottom line, there are a lot of factors that can influence where the brass flies, including the deflector, extractor tension, ejector tension, bolt speed, etc. Just my $.02.

    Grumpy, don't take this as a slam or even a dispute to your methodology. I just wanted to know your reason for thinking the N4 was over gassed. You're certainly entitled to your own opinion on the subject. Some people will agree, others will not. I'm not trying to call you out or create a dog pile here.

  8. #38
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    Quote Originally Posted by Tzook View Post
    I know my Noveske N4 isn't a TRUE middy, but FWIW I've never had an issue with it, and I shoot crap ammo almost exclusively. (Shout out for poor people!!!) Tons of Wolf, mainly.
    Are you running the intermediate gas system?

  9. #39
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    Quote Originally Posted by jstone View Post
    This is exactly my point. Someone got to it before i could. I did not say IG said anything. I do not put words in other peoples mouth. I said if someone reputable like IG or grant says the chart is a good way to diagnose overgassing or bolt speed i Will take back everything i have said.
    In other words, you don't have anything to add to the conversation other then what you're told by others. Got it.

    If it is such a good way to diagnose a problem why would you be hesitant to tell people. Probably because you know it is bullshit.
    No, I already explained this. I am hesitant to say because I didn't want to put up with this mindless bullshit mantra of "Ejection patterns are worthless" from people like you. Thanks for re-inforcing my beliefs that there are more "know nothings" then there are "Know somethings" on this site.

    Your entire view on this is built around what other people have told you rather then actually trying to read and understand what it is that I wrote. you cannot actually tell me WHY you think my diagnosis is incorrect based on what I said, rather your only mantra is that it's BS because someone else told you it is.

    Crawl back under your rock.

    I think it is stupid to run something till it breaks, but it is just as stupid to think your 100% operational firearm has a problem based on this chart that just popped up in the last couple years.
    Once again proving that you didn't read a goddamn thing I wrote. Congradulations, you just opened your mouth an proved me right.

    I agree that a system has an optimal functioning range, but without proper testing you have no clue if it was within parameters.

    Bottom line is there was no malfunctions (your claim), and you think it has a problem. It is obvious you believe yourself to be an SME. So regardless you Will continue to diagnose guns than run 100% to have some sort of problem.
    The bottom line is that you just don't get it. Machines don't have to "malfunction" to not be working "right". I like my guns to work "right". You may not and that's your ****ing problem, not mine.
    It is missing the point to think that the martial art is solely in cutting a man down; it is in killing evil. It is in the strategem of killing the evil of one man and giving life to ten thousand -Yagyu Munemori

  10. #40
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    Quote Originally Posted by mtdawg169 View Post
    Personally, I don't put any faith in the ejection chart. If GrumpyM4 wants to, that's his prerogative.

    The reason I don't have any faith in it is based on my own experience with an SR15. This gun is known to be under gassed. Mine runs fine with good brass cased .223 ammo. I can tell a difference shooting it with 5.56 vs .223. With weaker ammo, the gun almost feels sluggish & recoil is very soft, but it runs fine. There is no way that gun is over gassed. The Chart tells us my gun should eject past 3:00. It actually ejects between 1 - 2:30, depending on ammo.

    I've talked to KAC in the past about it and they attribute this to how the shell hits the deflector. They actually test cyclic rate with slow motion film to determine proper port size, so I'm confident in the design of the barrel. My upper shows signs that the brass is actually hitting the front edge of the deflector and bouncing forward. Bottom line, there are a lot of factors that can influence where the brass flies, including the deflector, extractor tension, ejector tension, bolt speed, etc. Just my $.02.

    Grumpy, don't take this as a slam or even a dispute to your methodology. I just wanted to know your reason for thinking the N4 was over gassed. You're certainly entitled to your own opinion on the subject. Some people will agree, others will not. I'm not trying to call you out or create a dog pile here.
    I get where you're coming from.

    If KAC has intentionally manufactured their guns to a spec that allows for ejection that is inconsistent with a properly running milspec gun, and have ensured that their bolt speeds are correct while doing so, then that means, if you ever do pay attention to ejection, that perception will have to change.

    If it's ejecting to the 1:30 ish normally, and then starts popping brass to the 4, then you'll start showing signs of severe undergassing through FTEs, failure to lock back, etc.

    On the other hand, should you start finding your brass hitting the handguard, you're going to be heading into overgassed territory real quick. This can also result in failures to lock back on the last round or worse, spent brass finding its way back into the ejection port.

    As long as you understand your weapon, paying attention to the secondary performance indicators can still help you diagnose issues.

    p.s. I think it's been pretty established by now that I don't acutally use the "chart". I use ejction patterns they way they should be used, as an indicator of the overall "health" of the gun.

    p.p.s. The way the brass hits the deflector is a function of several things. I.E. bolt speed, speed of the brass exiting the ejection port (strength of ejector spring vs. strength of extractor spring/ring, etc.)

    Typically, in guns with faster bolt speeds, the bolt travels further rearward before the empty casing exits the ejection port, causing it to impact the deflector closer to the port itself and eject further forward. You'll notice more wear on the deflector where it meets the ejection port, rather then equaly along the front or outer tip of the deflector.

    In guns with slowe bolt speeds, the empty brass will be leaving the ejection port sooner and impacting on the deflector closer to the outside tip, allowing it less impedence on its travel more towards the rear.

    All of that, of course, being with in spec milspec parts.

    If KAC is saying that their bolt speeds are within the proper cyclic rate for an AR/M16 and it's ejecting that far forward, then it's probably a function of a very strong extractor over-riding the ejector spring and allowing the bolt to travel further rearward before kicking the brass out of the ejection port.

    So long as this is understood, that's fine. But you still have an established baseline and you know WHY it does what it does. Meaning that armed with that knowledge, and understanding how ejection behavioral patterns still indicate changes in your system regardless of where its "normal" patterns are, you can still successfully use ejection to diagnose weakening springs and allow you to decide when you want them replaced to keep you happy and ensured that your gun isn't getting too terribly far out of optimal operating perameters.
    It is missing the point to think that the martial art is solely in cutting a man down; it is in killing evil. It is in the strategem of killing the evil of one man and giving life to ten thousand -Yagyu Munemori

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