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Thread: Brass pipe mandrels

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  1. #31
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    Photo of barrel mandrel and partially completed barrel:


    barrel_mandrel_1.JPG

    So far, barrel diameter has been modified to a straight tube design, and the barrel hood and lower lugs have been reduced enough to allow complete assembly. It still needs work, and a lot of tests and measurements need to be made, but it cycles manually with no interference.

    The color is due to Dicropan T-4 cold blue that I tested out on the straight portion.

    -

  2. #32
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    I would agree that it is better for all bushing type barrels to have a straight barrel, equal in diameter from the muzzle back to the lugs. When the barrel has a bell at the muzzle the barrel will hang down more when the slide is back causing the chamber end to point up slightly.

    CAW
    “If it ain't broke, don't fix it' is the slogan of the complacent, the arrogant or the scared. It's an excuse for inaction, a call to non-arms.” Colin Powell

  3. #33
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    Quote Originally Posted by CAWalter View Post
    I would agree that it is better for all bushing type barrels to have a straight barrel, equal in diameter from the muzzle back to the lugs. When the barrel has a bell at the muzzle the barrel will hang down more when the slide is back causing the chamber end to point up slightly.

    CAW
    When the slide is back it is not locked up and you are not going to fire it.

    The position 'in battery' is all that matters.

  4. #34
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    Quote Originally Posted by brickeyee View Post
    When the slide is back it is not locked up and you are not going to fire it.

    The position 'in battery' is all that matters.
    I disagree, chambering matters, and when the barrel hangs down at the muzzle the chamber end is up dragging on the slide. Barrels without the bell do not show all the scratches on the chamber end. Better is better.

    CAW
    “If it ain't broke, don't fix it' is the slogan of the complacent, the arrogant or the scared. It's an excuse for inaction, a call to non-arms.” Colin Powell

  5. #35
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    Commercial bushing mandrels suspend the mandrel between centers.

    Because the bushing is so short, I machined a short mandrel, turned true in the lathe chuck, and used two different clamping methods for the internal and external machining operations.

    The first photos are the mandrel as it was used to open up the bore of an oversize bushing to fit the barrel. The hose clamp was used to secure the bushing to the mandrel. The curved strip of material is "fish paper", a phenolic composite commonly used as an electrical insulator. It was used to protect the outer surface of the bushing from the hose clamp. Not shown is a narrow strip of metal shim around the mandrel to equalize the mandrel and bushing diameters where the hose clamp fitted over them.

    The outer diameter wasn't actually turned yet; the bushing was reassembled onto the mandrel just for the photo:

    barrel_busing_1.JPG


    To turn down the external diameter of the barrel bushing, the bushing was clamped axially, between the shoulder on the mandrel, and a conical brass bushing:

    barrel_bushing_2.JPG

  6. #36
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    Thank you for taking the time and effort to take and post those images showing how you did it. Pictures are usually worth at least a thousand words - especially when it comes to this sort of thing.
    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. #37
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    Quote Originally Posted by CAWalter View Post
    I disagree, chambering matters, and when the barrel hangs down at the muzzle the chamber end is up dragging on the slide. Barrels without the bell do not show all the scratches on the chamber end. Better is better.

    CAW
    The difference in the angle at the chamber end is very tiny numbers of displacement.

    The shell is not held that rigidly by the extractor and the slight movement does not appear all that important.

    Less is not always better.
    Last edited by brickeyee; 15th October 2017 at 12:26.


  8. #38
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    Quote Originally Posted by brickeyee View Post
    The difference in the angle at the chamber end is very tiny numbers of displacement.

    The shell is not held that rigidly by the extractor and the slight movement does not appear all that important.

    Less is not always better.
    I believe better, is better. Belled barrels are also noted for being dragged forward by the bushing before the breech face or barrel face contacts the barrel as it should. This causes a misalignment with the upper lugs and can cause failures to properly chamber. So, better is better.

    CAW
    “If it ain't broke, don't fix it' is the slogan of the complacent, the arrogant or the scared. It's an excuse for inaction, a call to non-arms.” Colin Powell

  9. #39
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    Quote Originally Posted by niemi24s View Post
    Thank you for taking the time and effort to take and post those images showing how you did it. Pictures are usually worth at least a thousand words - especially when it comes to this sort of thing.
    That's appreciated. I need to use pictures more.

    I neglected to remark on a couple things visible in the photos though:

    The narrow portion of the bushing between the locking lug and flange did not need to be turned, as it was not oversized and measured 0.699". This was fortunate, as that is a more difficult area to access for turning. The bushing is an Ed Brown.

    The two flats on the end of the mandrel screw are there to allow holding it with a 7/32" wrench, as even a large #4 Phillips screwdriver wasn't long enough to reach the head through the hollow lathe spindle.

    -

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