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Thread: Production fitted barrels

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  1. #1
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    Production fitted barrels

    How are barrels typically fitted on a production 1911?

    I am looking at the barrel from my Springfield MilSpec, and it appears that the bottom barrel lugs were never fitted to the gun.

    The bottom lugs both show a flange (burr) along the edges of the link slot, as if nothing was ever done after the link slot was cut. It's hard to imagine that the slot would have been cut last, after the bottom lugs were fitted.

    The only areas that show any sign of fitting are the top surfaces of the upper lugs, and the top surface area between the upper lugs and the end of the barrel hood. All other surfaces have a very fine matte finish, which look to be original to the barrel's production.

    Having control over their frame and slide specs, can a 1911 manufacturer also make barrels that are partially drop in fit?

    -

  2. #2
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    Bottom lug to frame is "supposed" to be the first step in fitting a barrel. Perhaps during assembly a quick clearance check is made...if it passes, the assembler moves on to the next step. The only fitting that I have ever needed to do is to the rear vertical surface of the foot.
    Beauty is skin deep but ugly goes right to the bone.

  3. #3
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    I don't think barrels are "fitted" at all in production 1911s. I believe they are all drop-in. Typically, the assemblers have a stack or bin of parts in front of them. They'll pick a part (such as a barrel) and test fit it to the receiver they're working on. If the resulting fit doesn't fall within the manufacturer's specs, they set that part aside and try another one.
    Hawkmoon
    On a good day, can hit the broad side of a barn ... from the inside

  4. #4
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    Agreed. Production model guns are not much "fitted", they are assembled.

    In this 1942 article, the slide is described as being "filed up" to fit a receiver, then checked to fit on 30 others. I doubt even that is done on commercial copies.
    Unfortunately it does not go into detail about final assembly.
    http://forum.m1911.org/temp/1911manufacture.pdf

    Colts made during the period when slides were serial numbered to match the receiver will often be found with slides a few digits different from the receiver. This is usually explained (excused) as being due to fit tests in which parts of a number of guns were mixed and reassembled. The other legend is that they were cleaned in a group and reassembled with no effort made to matching parts.

  5. #5
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    If anything, I think modern fabrication techniques and processes makes fitting even less necessary than it might have been in 1942. With CNC machining centers, the machines are set up to a tolerance of 1/10,000 for each thousandth they want the finished parts to hold. In other words, the machines are held to a tolerance ten times tighter than the parts being produced on that machine.

    I know that over the years I've swapped Colt slides and barrels onto different Colt receivers, and Para-Ordnance slides and barrels onto different Para-Ordnance receivers, and I've never found a combination that didn't fit together within tolerances, and function perfectly.
    Hawkmoon
    On a good day, can hit the broad side of a barn ... from the inside

  6. #6
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    IMHO, almost all of this ability to interchange parts is a not a direct result of CNC techniques (although it certainly does help) but the fact that the various manufacturers have free access to Army Ordnance blueprints for the Government Model M1911A1 - and usually follow them in those areas critical to interchangeability. Without those blueprints it would be up to each manufacturer (and there are dozens of them around the world) to dream up its own blueprints. As Jerry Kuhnhausen wrote, they are the only blueprints we have and the only blueprints we will ever have for an M1911A1. Or something close to that.

    And I'm not talking about those custom made and fitted Bullseye and race guns - just your average run-of-the-mill 1911.

    Just my 2¢ worth.
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]

  7. #7
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    Quote Originally Posted by niemi24s View Post
    IMHO, almost all of this ability to interchange parts is a not a direct result of CNC techniques (although it certainly does help) but the fact that the various manufacturers have free access to Army Ordnance blueprints for the Government Model M1911A1 - and usually follow them in those areas critical to interchangeability. Without those blueprints it would be up to each manufacturer (and there are dozens of them around the world) to dream up its own blueprints. As Jerry Kuhnhausen wrote, they are the only blueprints we have and the only blueprints we will ever have for an M1911A1. Or something close to that.

    And I'm not talking about those custom made and fitted Bullseye and race guns - just your average run-of-the-mill 1911.

    Just my 2¢ worth.
    If we're talking about simple, regular production, middle of the road 1911s, then presumably the gun maker only has one source for barrels... so they can order them to whatever specs they think will suit them best, knowing what their frames, slides and other parts are like. Whether or not the parts happen to agree with military specifications for the M1911/M1911A1, is another matter.
    Too many people miss the silver lining because they're expecting gold.
    M. Setter

  8. #8
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    If so, then the probability of parts interchange with other makes of 1911 would seem to be reduced. That manufacturer is then headed down the path to a time before the industrial revolution - when the chances of part interchange were about the square root of zero point squat.
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]

  9. #9
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    Parts interchanging between pistols made by a single manufacturer is one thing. The Army's intention was for parts to interchange between 1911s of different makers. That's another order of magnitude.
    Too many people miss the silver lining because they're expecting gold.
    M. Setter

  10. #10
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    Of course, and it's your second scenario that I was referring to. On the other hand, an extreme example of the first scenario would be somebody making a "1911" to specifications just far enough off of Ordnance specs that only his replacement parts would fit. None of all the others from other 1911 manufacturers would fit - including the host of aftermarket parts. While those "1911''s might run 100% and be real tack drivers, I've a feeling their production run would not be a long one.

    Those Army Ordnance drawings (with dates spanning more than 50 years) define what an M1911A1 is. Anything else is ersatz. Anything!
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]
    Last edited by niemi24s; 14th September 2017 at 10:29.


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