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Thread: Link Fitting - Voice of Experience Needed

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  1. #1
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    Link Fitting - Voice of Experience Needed

    I'd like to describe a barrel/link fitting situation and ask for advice. The pieces are: Kart NM barrel, Caspian Gov. slide and frame. I removed metal from the upper lug recesses of the barrel while watching the amount of engagement increase slowly. I now have about .045" lockup, and can see the barrel hood is just touching the slide behind the #1 lug face. At the same time the firing pin port is perfectly centered.
    Then, the barrel feet were fit (minus link) to stand on the slide stop with the slide in battery.

    At this point I installed a standard .278 link and noted that the lower link hole is about .010" "below flush" on the lug feet. That is, the slide stop will not go into the frame because the link hole sits too high. In fact, I have to go to a #5 link to get a flush fit with the barrel feet in lockup.

    So, if I remove metal from the feet, to allow a .278" link to be flush, the barrel upper engagement will be decreased and the firing pin hole will not be centered. The barrel seems to drop clear by the 1/4" mark with the #5 link but I am uncertain whether the long link will introduce other problems down the line.
    Use the long link? Toss the barrel and start over?
    Thanks for your suggestions!
    -Lazarus
    "Do not fix that which is not broken."

  2. #2
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    I am no expert on barrel fitting, but I would first try the #5 link instead of filing the barrel legs. Remember the golden rule, always work on the cheaper component.

    My logic says that it is important to have good lock-up on the lugs, and the barrel feet to ride the slide stop shaft for positive lock-up. The link is used to unlock the barrel. If the #5 unlocks the barrel properly, why destroy the good lock-up you had?
    John Caradimas SV1CEC
    The M1911 Pistols Organization
    http://www.m1911.org

  3. #3
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    Yep

    That was my thinking as well, and it made sense to me. Make the barrel stand on the slide stop, pressed hard against the upper lugs, after centering the firing pin. That's what we've been shooting for all along, right?

    Then, after the barrel goes into battery with a solid vertical lockup, you don't really have much to say about your link dimension. I can see that standard parts can be forced to work at the expense of a tight vertical barrel lockup. So many things to control all at once!

    -Lazarus
    "Do not fix that which is not broken."

  4. #4
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    Talking

    No offence, El Commandante, But over the years I've noticed that working on the "right" part gives much better results and you don't ruin the cheap part.

    Looks like a lot of frames and slides are out of spec nowadays. The VIS is cut for a standard link and barrel and slide lug engagement takes a back seat. If you get decent lockup, you may have to go with a long link and run into problems with the VIS and or frame bridge. Or cut the lower barrel lug to fit a shorter link and give up your solid lockup. Nice choices. You will probably have to remove some material from the frame somewhere. VIS I suspect because that longer link may not provide the needed barrel and slide clearence since the larger arc of the longer link will move the impact point of the lower barrel lug back and will stop the barrel at a higher position than a shorter link. I've been told by someone I trust that that bowtie is just a cheap and cheesey way of creating a VIS and I concur. And after John Browning got beat down on his prices, he probably had to take some short cuts. I think another poster in a different thread nailed it when he concluded that the bowtie currently in vogue was not the proper solution to creating an Impact surface. But do what you must do. Just my opinion anyway. And worth every penny you paid.
    xxxxxx Iron bottom sez; Don't let your Rat Terrier hang around with college boys.

  5. #5
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    No offense taken, as I said, I am nowhere near being an expert in barrel fitting. What I just said was, that before cutting the barrel legs, I would first check if the #5 links is OK. It may be possible, as you say, that with the longer link, the barrel doesn't come down properly, or you may be surprised to find that it does. What do I know????
    John Caradimas SV1CEC
    The M1911 Pistols Organization
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  6. #6
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    A point I have not seen discussed.
    Removing .005"-.010" from the back side of the lower barrel lugs.
    .100" thickness is fine.
    Can give you that extra necessary linkdown when using a longer link.

  7. #7
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    I believe you are exactly right about using the #5 link, El Commandante. If the lockup is good and the firing is centered correctly, the longer link is the only way to go in my opinion. I was just saying that the price of a part doesn't always determine or fix the problem. I've got the same situation going on. But with a .288 link, the bottom barrel lug is impacting the VIS way too high and is affecting the barrel/slide clearance when out of battery. I do not want to give away any lug engagement to correct this problem since this would lead to a loose lockup and borderline barrel and slide lug engagement. As the last poster mentioned, taking some material off the back of the bottom barrel lug may correct the problem, but I really didn't want to cut away this area. There is a local machine shop and I am going to see if they can or will move the VIS back. Who would ever know anyway? And if it doesn't work out, I've got some TIG rod for 4340 and can probably scrape up the ducats to machine away this unfortunate decision.
    xxxxxx Iron bottom sez; Don't let your Rat Terrier hang around with college boys.

  8. #8
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    Machining back the lower lugs or the VIS has the same effect.
    Realize this though......you will also be decreasing the feed ramp to barrel gap. Many times it is a compromise between feed ramp depth/angle, gap and cartridge support.
    It seems as if the forward wall of the mag chute on Caspians is a bit too far forward. This leads to a further compromise as described above.
    It's a balancing act. Borrow a bit from Peter to pay Paul.

  9. #9
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    Juggling the variables

    Thanks for the comments, gents. Using the #5 link, I find that if I mark the rear of the barrel bottom lugs and the belly of the barrel with Hi-Spot, I do get a mark on the VIS and, suprisingly very little if anything on the main bed itself. The barrel does not stand on its feet, because the feet have been shortened too much already by Kart. The barrel seems to be stopping on the belly that is forward of the lugs, and I'm not sure whether that is OK. Seems as though a little material removal on the bottom of the barrel will relieve it enough so the timing will be correct.

    The Caspian frame has been machined with a bow-tie VIS, although it is not as deep as some I've seen. I don't like it one bit, as the contact area has been reduced to a very tiny area, albeit "correctly" located at the top of lugs.

    Sure is fun to juggle all these variables around. At this point I freely admit that I don't have the experience to decide which dimensions are most important (except for headspace). I'm going to stick with a hard vertical lockup, however, since that gives me the maximum lug surface to bear the forces of firing.

    -Lazarus
    "Do not fix that which is not broken."

  10. #10
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    Link

    For now, use the #5 link and check the linkdown/drop timing to see if the barrel is clear of the slide at .250-inch of slide travel. If it doesn't clear sufficiently, check to see if the barrel's vertical drop is being stopped by the link in compression, and being held off the bed.

    If that looks good, flip the gun upside down and pull the slide rearward briskly.
    The barrel should disengage and link down as smoothly as it does when held upright. If it doesn't, you've probably got a VIS mislocation...too far forward.
    Of several Kart barrels that I've used...both Easy-Fit and full or "Hard-Fit" none have had a mislocation of the lower lug too far rearward.

    The bow-tie cut is a quick-fix for a forward VIS, and it works nicely. The issue that I have with it is that it leaves a very narrow strip of material at the top of the VIS..where it takes the full impact of the barrel...and it deforms quickly under hard use, until eventually, the VIS is too far rearward.
    The barrel starts to stop on the link. The link stretches and effectively lengthens to the point that it's too long to vertically disengage the barrel from the slide at the right time. Or...it reaches the breaking point and lets go, and the barrel can't disengage, and the upper and lower lugs both receive the full impact of the slide. One or two such crashes almost guarantee a sheared upper lug or cracked lower lug within a few thousand rounds...or even a few hundred, depending on the barrel steel. Less likely, but also possible is a cracked slide at the first lug adjacent to the ejection port.

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