Gunsmithing Loose barrel threads

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Lets say that a guy wanted to try to chamber his own barrel & lets say he cut the threads a little under sized. Purely hypothetical. In no way did this actually happen :)
Is there anything that can be done other then setting it back & starting over? The threads aren't so loose as to worry about safety but worried about accuracy.
I assume wrapping the threads in teflon tape or something is a no no.
 

TxShooter63

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I have dealt with this exact scenario. A gunsmith undercut my barrel tenon threads slightly. This caused POI shift each time the barrel went from cold to warm. The first shot would be 1/2" high and the next 4 through one hole. I wrapped threads with Teflon tape and the barrel remained a sub 1/4" rifle for the next 2000 rounds until it expired. (.260) How much Teflon is a matter of testing. It should thread snuggly but not bind. Start with 2 wraps and work up. You will be pleasantly surprised how well the rifle will shoot once you do this.
 

J E CUSTOM

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In my opinion, Setting it back and re-threading it would be the best and would eliminate second guessing if it did not shoot well.

J E CUSTOM
 

heavy barrel

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I have dealt with this exact scenario. A gunsmith undercut my barrel tenon threads slightly. This caused POI shift each time the barrel went from cold to warm. The first shot would be 1/2" high and the next 4 through one hole. I wrapped threads with Teflon tape and the barrel remained a sub 1/4" rifle for the next 2000 rounds until it expired. (.260) How much Teflon is a matter of testing. It should thread snuggly but not bind. Start with 2 wraps and work up. You will be pleasantly surprised how well the rifle will shoot once you do this.

Thanks Tx. That is what i was worried about. Teflon tape was the first thing that came to mind but wasn't sure if it would cause any other problems. Glad to here it worked for you. I think I will give it a try & see what happens. I know setting it back would be the best solution but the barrel is done now & I might as well give it a try. I'm a palma shooter & need all the velocity i can get. I can always set it back later if need be.
 

Bloody_Tailgate

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Thanks Tx. That is what i was worried about. Teflon tape was the first thing that came to mind but wasn't sure if it would cause any other problems. Glad to here it worked for you. I think I will give it a try & see what happens. I know setting it back would be the best solution but the barrel is done now & I might as well give it a try. I'm a palma shooter & need all the velocity i can get. I can always set it back later if need be.

You mean you'll "hypothetically" try the Teflon tape to see if it "hypothetically" works.
 

heavy barrel

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Oh, ya, that's what I ment to say. This is just a "what if" kind of thing, just in case I run into someone that has this problem:)
 

skeetlee

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did the tape work? i cut a tenon a little small one time. the barrel shot fantastic!! so well in fact i thought about doing the next barrel the same way. lol i didnt though. lee
 

bward

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did the tape work? i cut a tenon a little small one time. the barrel shot fantastic!! so well in fact i thought about doing the next barrel the same way. lol i didnt though. lee
My experience as well. One of the most consistent and accurate barrels I've shot was one that I cut the threads a little too deep on. I don't think a slightly loose thread makes any difference at all.
 

buffybuster

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My experience as well. One of the most consistent and accurate barrels I've shot was one that I cut the threads a little too deep on. I don't think a slightly loose thread makes any difference at all.

One time the threads got cut a bit loose (was just a bit tight, so took a little off... too much). I torqued the barrel a bit tighter than I usually do. Shoots great. I think as long as the shoulder and the receiver face are square, it makes up for a bit of slop in the threads. Ideally a close thread fit is desirable, but maybe it's not absolutely necessary, if the receiver and barrel shoulder are square.
 

LongRifles Inc.

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    Years ago I had a POS lathe to deal with. Almost .100 of backlash on the cross slide to deal with.

    One day id had enough. I sweated a pile of silver solder into the bronze nut as a buddy ran the screw back/forth with a big drill. Just kept the heat on and slowly cooled it while he went at it.

    That lathe still works great and its been over a decade.

    So, maaayyyybbbeee you could do the same to your tennon and just recut the threads. -dunno, never tried it.

    Nother idearz;

    Whut if you turned down the tennon to say 15/16 and threaded it for a fine pitch, something like a 28 sounds good. Grab a piece of 4130/4140 and turn identical ID threads. Now screw it on, recontour the outside to your tennon, thread accordingly, and march on down the road like it never happened.

    I have done this on a personal gun when fitting up an old take off barrel that had been goofed up.

    Shoots great and my face is still attached to my skull.

    Good luck

    C.
     

    cal50

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    I re-barreled a 1917 that shot very accurate but the barrel was really pitted bad. My friend had a new barrel and needed it cranked on. Once I broke the barrel loose from the action I was amazed it did not fall out of the receiver. The threads were horribly matched and the barrel would wobble BIG TIME once broke loose. The shoulder is what kept it locked on the receiver but I was amazed at how poorly it fit and still shot well.
    Sloppy threads and over torqued.


    Its bad machine practice having sloppy threads and it will never help accuracy but if the barrel it tight and headspaced correctly try it and see hoe it shoots.
     

    Red_SC

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    Its bad machine practice having sloppy threads and it will never help accuracy but if the barrel it tight and headspaced correctly try it and see hoe it shoots.

    As long as it's safe, shoot it. The threads just provide clamping force, the receiver face keeps it straight.