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Damaged upper tang screw hole

kimikimi Member Posts: 44,723 ✭✭✭
edited February 2015 in Ask the Experts
I need help with fixing an upper tang screw hole. While cleaning an old Winchester I seem to have damaged the upper tang screw hole. The screw will work fine for about three plus turns and then stops. I think that I might have torqued it too much. At the bottom of the screw there is slight damage to a thread, when I try another screw, it works well for about three turns and then meets resistance. I can't see the damage to the threads in the hole, but it is bound to be there. Can this be fixed by a competent gunsmith without having to drill a larger hole?

Thanks for any help.
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    rufe-snowrufe-snow Member Posts: 18,650 ✭✭✭
    edited November -1
    Your description of the problem. With the threads binding after 3 turns. Is the classic description of trying to put a wrong size screw into a threaded hole. i.e. the outside diameter of the screw is correct but the threads per inch of the male screw is incorrect for threaded hole.

    If the rifle is a valuable collectors item, take it to a knowledgeable Winchester gunsmith. If it isn't you can fix it yourself. If you have the correct tap, and original sized tang screw. What ever you do. You don't want to mess up the female threaded hole, anymore than it has been all ready.
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    kimikimi Member Posts: 44,723 ✭✭✭
    edited November -1
    Thanks rufe-snow, I did not know that this description was a classic example of the problem as you have explained it. This is the first time I have ever taken the screw out. It came out in a nice smooth fashion as expected.

    I'll ask around to see if anyone can recommend a competent Winchester gunsmith to work on this for me as you suggest, and then check him out for other positive references as well prior to trusting him to handle this for me.
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    charliemeyer007charliemeyer007 Member Posts: 6,579 ✭✭✭
    edited November -1
    Gun screws are a finer thread than you usually find at the box stores.

    The hole might need chased with a tap. A new screw might be made (or found) with oversized threads to fit the hole better.

    Holes are welded shut or bushed and then drilled and tapped to factory size; moving up one size screw is often the cheap way out (does not enhance collectors value). I don't like glue based filler's on guns.

    See a Competent Gunsmith is a safe answer.

    added If the metal is pulled out of the hole, it could be flowed back into position with a punch, then chased. An oversized screw could be made to fit the remaining threads in the hole. Most thread cutting dies have a screw in the side that allows for cutting oversize threads. Often a screw several sizes larger is the donor. The head is dressed to proper size/shape, the shank is turned to desired diameter the threaded to the "oversize".

    Any competent "Gunsmith" should be able to preform the task, "Gun Assemblers" not so much.

    Pic's would be nice. Lot of difference between 6-48 and a 10-36
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    Bert H.Bert H. Member Posts: 11,279 ✭✭✭
    edited November -1
    I would chase the threaded hole in the upper tang with the correct size tap (6-48), and replace the screw. I am quite sure that will fix the problem.
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    kimikimi Member Posts: 44,723 ✭✭✭
    edited November -1
    I'm back again with the same problem. I had a gunsmith chase the hole with a size 6-48 tap with no luck. That said, I have another reference that states the correct size tap for the Model 1890 is the 10/36. I never imagined that something that appears so simple to me could create such a problem.

    For example, this gun came with an "early" Lyman tang sight, and the heads of the screws for the early ones are not as thick as those for the later ones, but this is another problem altogether.

    More on the situation that I might should have mentioned the first time around since I believed that both upper tang screws would be of the same thread size: The hole that is damaged is the one for the short upper tang screw. The screw that I attempted to put back in was the one that had come out in the first place. In my attempts to put it back in, I think that I torqued it to the point that the edge of the hole has raised a bit, which I'd like to see repaired, along with the screw hole being fixed.

    It seems to me that a gunsmith, most any gunsmith should be able to fix these problems, but I don't have the confidence to entrust such a high quality expensive receiver to just any gunsmith, as I have one less than satisfying experience with this one, and another one that had a total lack of understanding about what a modification would do to a collectible firearm, plus I have heard about parts being exchanged and the like. I'm to the point of realizing that I might have to ship the receiver to someone like Turnbull, but that's from one coast to the other. So my question to you ATE members is: Do I have that big of a problem, in what appears to me to be the type work that most any apprentice gunsmith should be able to fix in a professional manner, or do I need a professional like Turnbull? Anyone know of a "competent" gunsmith in the Renton or Kent, Washington area?

    EDIT:

    [:D] Mobuck, it could be just my memory too! It's been awhile since I've given this issue any interest. But he did "chase the hole." [:D]

    charliemeyer007: I'll try to get some pics up in the next day or so. Thank you.

    ruff-snow: I found one gunsmith that has a good rep in my area based on a number of inquiries, but he has retired!

    Greg: Thanks for the offer to help with the measurement and the other notes. The one concerning trimming the screw would work well with a plug screw or the sight screw!

    To everyone that responded to my queries - Thank your for your time and knowledge!!!!!!!
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    MobuckMobuck Member Posts: 13,860 ✭✭✭✭
    edited November -1
    "I had a gunsmith chase the hole with a size 6-48 tap with no luck. That said, I have another reference that states the correct size tap for the Model 1890 is the 10/36."

    Anyone with a "gunsmith" business would notice right away if he tried a 6x48 tap in a 10x36 hole.
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    MG1890MG1890 Member Posts: 4,649
    edited November -1
    On an 1890 the upper tang only has (1) threaded hole, and that is only used to mount a tang sight. Otherwise it is plugged. It is larger than 6x48, if necessary I can measure one for you.

    Why not just trim off a factory plug screw so that it will screw in flush to the top of the tang?
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