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Thread: Controlled Feed Principles

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  1. #1
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    Controlled Feed Principles

    Guess it's time to do a thread on the Controlled Feed principle. Seems that many don't have a full grasp on exactly what it means and how it works. So...since part of the mission of the forum is to educate...Here ya'll go.

    The system is actually pretty simple. It's in understanding how it works that throws so many people off the trail. Simply put...The cartridge must remain under full control of the gun from the time the magazine is locked in until the empty case clears the ejection port.

    Much is made of the angled feed causing problems. Much ado about nothing. It's not supposed to feed in a straight line. Or another way...The cartridge is SUPPOSED to dip into the feed ramp. That's part of how it's kept captive as the magazine starts to lose control of it. The feed ramp angle is precise. 31 degrees + 1/2 degree, minus nothing, at a prescribed depth of .400-.420 inch from the top of the frame rail


    As the bullet nose dips and strikes the ramp, it's under tension...for lack of a better term...between the slide and the ramp. The magazine still has a grip, but it's gradually relinquishing that grip...and something has to take over. Nose-diving into the ramp keeps linear pressure on the cartridge between the ramp and the slide. Knock the barnacles off your thinkin' caps here.
    If the round was supposed to feed in a straight line, the gun wouldn't even need a feed ramp, much less a ramp at such a precise angle and depth. Note that the ramp is also curved. That works to keep the bullet nose contained on the sides, and keeps it tracking straight. The curve and the angle literally aim the round into the chamber.

    The bullet ogive is also important. The angles have to work together in order for the controlled feed to function as intended. Bullet length forward of full diameter is also important. If the cartridge is too far forward in the magazine when it hits the ramp, full control is compromised...or lost.

    The corner at the top of the feed ramp also must not be altered except when correcting the feed ramp angle. If the cartridge isn't deflected upward into the barrel ramp...often mistakenly referred to as the "Barrel Throat"...at a steep enough angle, it strikes the barrel ramp too low.

    When it does that, it pushes the barrel forward...and when the barrel moves forward too early, it also cams UP too early. This increases the angle of cartridge entry and brings about the well-known Three-Point Jam. A too-long link has the same effect, but with different mechanics.

    If the round hits the barrel ramp above center, it works to keep the barrel down against the frame bed, keeping the angle correct for the horizontal break-over and chambering. Once the cartridge is horizontal, or neraly so, and deep into the chamber, the barrel is free to cam into
    lockup. The noted gap between the lower edge of the barrel ramp and top corner of the frame ramp helps to insure that the cartridge will enter the barrel ramp above centerline and well forward of the corner. This is also an aid to keeping the barrel down in the bed during the initial feeding phase.

    The angled approach is also a requirement for the rim to get under the extractor correctly. If the feed angle is reduced...straightened out, as some are fond of saying...the bottom corner of the extractor hook is positioned very close to the rear face of the rim. A small variation in case rim can make contact there, and cause a stoppage. Lightly radiusing the bottom corner of the extractor hook nose is done to provide a little extra clearance there...for the reason of varying case rim diameters...but it won't take care of an incorrect feed angle. The angled ramp insures that the rim approaches the hook from well underneath.

    Okay...the cartridge is deflected up into the chamber. The forward radius of the bullet ogive is in contact with the roof of the chamber...but what it that cartridge is not only too short, but the ogive is also too wide. The short cartridge moves farther out of the magazine when it takes its necessary dive. That makes the dive steeper, and the resulting upward delfection is also steeper. The bullet ogive hits the chamber roof farther back and at a steeper angle...and you have another variation of the Three-Point Jam...except this one is jammed tighter. In extreme cases, this one can almost mimic the Bolt-Over Base failure to feed.

    Positive magazine control of the round depends largely on spring tension. This isn't an issue when the magazine is past half-full, but as the magazine loses rounds, the tension degrades. Most important in controlling the last round...when spring loading is at a minimum...it requires a helping hand to prevent the last round from moving too far forward and possibly escaping
    under the inertial effects of recoil, which...in a .45 caliber 1911...is a pretty violent, slam-bang affair. That helping hand comes in the form of a tiny little bump on top of the magazine follower. Without it, the cartridge is free to roam...and often does. It may not cause a stoppage if it moves too far forward...even if it doesn't completely escape...but it feeds at a straighter angle, which...as we've already covered...isn't good. It's not good for reliability and it;s not good for the extractor. The extractor wasn't designed to snap over the rim...not even the external extractors. The externals are simply more tolerant of the occurrence, but they'll still suffer damage if forced to do it for very long. At the least, the coil springs that drive them will
    weaken much faster because they're being compressed farther than they're supposed to. Some may even compress enough to go into coil bind...which damages a coil spring quickly.

    So, in summary...

    The round is properly under forced, positive control from at least three points from the instant the slide hits it.
    By steps:
    1...Slide, magazine lips, and spring tension.
    2...Slide, feed ramp, and magazine lips/tension.
    3...Slide, extractor, and barrel ramp.
    4... Slide, extractor, chamber roof and the top corner of the barrel ramp.
    5...Slide, extractor, chamber walls, and chamber shoulder.

    If the gun loses partial control of the cartridge from any one point...due to whatever is incorrect... it sacrifices a percentage of the reliability that the gun was built with.

    Common wisdom has stated that the 1911 was designed to feed hardball, and any variation of that bullet shape causes problems. That's partly true, but it's not the fact that the bullet doesn't have a round nose that causes the problems. It's incorrect ogive geometry too-short overall length of the cartridge that does it.

  2. #2
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    ding ding ding...the lights on but for how long?

    Ok Johnny,
    I'm gonna try this question, ain't never made a question that sounded too intelligent before but now I might just have it...

    I had a box of rounds that if they were cycled through the chamber once as I did while checking the tweak on my new extractor, it actually pushed the bullet itself deeper into the casing. When I shot these rounds 1 in 3 gave me the 3 point jam. If I read your post right then the shorter rounds were jumping to too high of an angle and binding the round on the casing side as the nose of the round was too shallow on the roof of the chamber?

    Fingers crossed...

    Brian

  3. #3
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    I understand what you are driving at Johnny. Polishing the feed ramp, throating the barrel, and changing anything about the original design of the 1911 (including aftermarket magazines that do not follow the original design) to make it work or work better is a band aid to a larger problem. If a 1911 is not feeding correctly altering the frame or barrel throat angles would not be the best course of action to try and correct the problem. Am I close?

  4. #4
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    re:

    Gottriplets...Bingo! While the gun is pretty forgiving of cartridge overall length, it isn't without limits. If the round was a little shorter than optimum to start with, when it was made shorter by the cycling action, it probably went past that limit. Also: A round that's much shorter than 1.220 inch AND has a flat nose profile...like a hollowpoint...is more likely to cause bullet telescoping to occur. Round-nose bullets are a bit more forgiving of length,
    but 1.200 inch is a good minimum to stick to, and even that will give trouble in some guns.

    Hunter,

    No. Altering the frame ramp angle isn't something that the casual hobby smith should try. That's what gets a lot of guys in over their heads when using the Dreaded Dremel to "polish" the ramp. The barrel ramp angle isn't nearly as critical, and allows a little more leeway in reducing the angle...but that has a definite limit too. Lower it too much, and the forward corner moves too far into the chamber and case head support is lost. if the static headspace is much beyond mid-spec, you risk blowing a case head.

  5. #5
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    Johnny, does it mean that it would be better to use a round nose bullet than a hollowpoint? pardon for my ignorance, I'm a newbie and just got my 1st 1911 .45 yesterday. Thanks
    _________________
    jok

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    Great post.

    Is this not true for all pistols more or less?

    I'm told the Beretta has a 'straighter' shot into the chamber. But, the cartridge still has to be controlled at all phases...correct? Simply, different type of extractors, feed angles, timing is different to accomplish the same effect as a 1911!

    Some useless thoughts.

    We talk about hardball being a reliable feeder, which it is, but if push came to shove, I'd vote for a 200 gr. SWC, proper length, being AT LEAST as reliable as hardball. They feel "slicker" going in.

    Perhaps the mags that hold the bullets higher is much to do about nothing!

  7. #7
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    Quote Originally Posted by jok
    Johnny, does it mean that it would be better to use a round nose bullet than a hollowpoint?
    I think that at the most simplest level, the answer would be "Yes". If I'm not mistaken, the original design of the 1911 predates hollow-point ammunition, or if hollow-points were available, Browning didn't intend for them to be used in the 1911.

    That being said, full ball or FMJ rounds do feed better. But that's not to say that a JHP won't work in the 1911 - many of us know to the contrary. But when you deal with bullet shapes that differ from the FMJ, then you add in a new dimension of feeding issues. And as many of us know, some brands of non-FMJ rounds work in some guns but not in others. And two identical 1911s may have different results even using the same brand of JHP.

    So it is "better" to use FMJ over JHP? I wouldn't say "No", but you need to experiment with different brands and see which one(s) work with your particular gun before trusting your life with it. On the otherhand, I know my Mil-Spec shoots the Winchester JHP just fine - but I've opted to only load FMJ because I don't want to run the risk of an unforeseen feeding problem when the moment counts.
    "I calculated the odds of this succeeding versus the odds I was doing something incredibly stupid, and ... I went ahead anyway." - Crow T. Robot
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  8. #8
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    Round Nose

    Quote Originally Posted by jok
    Johnny, does it mean that it would be better to use a round nose bullet than a hollowpoint? pardon for my ignorance, I'm a newbie and just got my 1st 1911 .45 yesterday. Thanks
    _________________
    jok
    Howdy jok,

    No. It's not the nose shape so much as it is the ogive geometry. After a couple decades of arguing with the wide cavity, large ogive radius of the Speer 200-grain Flying Ashtray, and then the truncated cone of the earlier
    Hydra-Shok, the ballistic engineers have seen the light, and redesigned the hollowpoints' ogive shape to closely follow that of hardball. They've also
    kept close enough to spec on the cartridge overall lengths to work with the frame and barrel ramp angles.

    I have several original, as-issued USGI pistols that will function perfectly with
    the Winchester Black Talons, Ranger Talons, and the standard 230-grain hollowpoints, as well as Remington's Golden Saber design. The interesting thing is that, they'll feed into the unmodified and unpolished ramps from the
    original "Hardball Only" magazines.

    Remington hit the
    magic number when they introduced the Golden Saber, and the others have followed suit.

    Auto45...
    The Beretta isn't a reliable controlled-feed design, and is more geared toward the push-feed/snapover principle, and it works very well in that. The way to determine the answer is to turn the gun upside down and hand-cycle a few rounds. If it's controlled, it won't make a difference. If it's not, it'll hang one up within a few rounds. And yes...The trick magazines that "correct the problem" by straightening the angle out are much ado about zip. it's a band-aid fix at best...and an expensive one...and it can cause problems of its own with the extractor if things are a little out of kilter. It can probably work pretty well IF the pistol is set up to operate with it. So, it may require fine-tuning to allow for the different feed angle.

  9. #9
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    Quote Originally Posted by 1911Tuner
    The way to determine the answer is to turn the gun upside down and hand-cycle a few rounds. If it's controlled, it won't make a difference. If it's not, it'll hang one up within a few rounds.
    Ooh! Now I've got something new to try when I get home. MrsKey is gonna look at me all sorts of funny tonight!
    "I calculated the odds of this succeeding versus the odds I was doing something incredibly stupid, and ... I went ahead anyway." - Crow T. Robot
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  10. #10
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    Tom/Johnny
    Thanks for a quick and detailed explanation to my question, really appreciate it. I really need to learn more, and since I'm basically new to the world of 1911 I would probably stick 1st with the basic which is the FMJ until such time that I could already speak in authority just like the two of you.
    Once again my thanks to both of you.
    ________________
    jok

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