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Hand tightening a mauser barrel?

Discussion in 'Gunsmithing and Repairs' started by morcey2, Feb 3, 2012.

  1. morcey2

    morcey2 Well-Known Member

    I have a Yugo K98 receiver that is going to be a 257 Roberts very, very shortly. I have a Adams & Bennett barrel for it and it should be heading over to Mark Skaggs at Skaggs gunsmithing here in a week or two. I haven't rebarrelled anything but I've done lots. (and lots. and lots) of work on cars, engines, etc so I know what a bolt and nut should feel like when they're threaded together.

    My understanding is that for most mausers, the barrel should be able to be screwed into the receiver with a small amount of force until one or the other of the shoulders make contact. This one goes in about one full turn and then stops. I haven't tried to force it, but as soon as it stops, it is difficult to remove. The threads on both the barrel and in the receiver are clean and don't look to be damaged at all. This is new terrain for me, so should I be worried at all?

  2. NCsmitty

    NCsmitty Well-Known Member

    You should let Mr. Skaggs worry about fitting the barrel, as he has done a bunch.
    You're likely experiencing an interference fit due to the 60 degree thread of the barrel fitting the 55 degree thread of the receiver, I'm guessing. This is not uncommon, and some use a lapping compound to work the threads for a fit, while others with the equipment, touch up the threads on a lathe.
    Just think about the loads that you plan to use, along with the accessories, and how much fun you're going to have with your new rifle.

  3. Zeke/PA

    Zeke/PA Well-Known Member

    This work in my humble opinion, should be left to a Gunsmith REALLY expirenced in these matters.
    I was taught when barrel fitting, to have the reciever "screw on" about 4 turns by hand followed by final tightening in a vice using an action wrench.
    THEN we come into the headspace arena which is of course another ballgame.
    Not a real problem if done correctly and guidelines are followed.
    In truth, there are a couple of things that must be checked out before trying to fit a pre-turned, pre-threaded barrel but once again, a COMPETENT Gunsmith is on top of all of this.
  4. HankC

    HankC Well-Known Member

    That is what I had to do.
  5. morcey2

    morcey2 Well-Known Member

    thanks everyone. It's headed to Mr. Skaggs early next week, so I'll let him worry about it. I was just a little unsure of whether the barrel should be able to thread in by hand.

    Looking forward to the new rifle! I picked up some brass today.... and I don't even have the reloading dies yet.

  6. dirtyjim

    dirtyjim Well-Known Member

    mauser threads vary so much that i always thread the barrels for that particular receiver unless i just happen to get a smokin deal on a prethreaded barrel and it just happens to fit.
    skaggs doesn't charge much over to thread, chamber and crown compaired to what he charges to install an pre-threaded & short chambered barrel. with his prices i think it would be better to have him thread a blank to your receiver but since you already have the barrel its a little to late.

    as far as how tight the barrel should fit goes i cut the threads on mine so the will thread all the way on by hand. once i get real close i start taking about .0015 off per pass untill it will thread all the way on. once its butted up i make two marks 1/8" apart, one on the barrel shank and one on the underside of the receiver. i use a barrel vise and action wrench to align the markes and consider it as tight as it will ever need to be.

    some people like to cut the threads till it will go on a few threads then use the barrel vise and action wrench torque it on the rest of the way, i'm not one of those people.
  7. Zeke/PA

    Zeke/PA Well-Known Member

    Correct me if I'm wrong.
    Mauser threads vary BECAUSE they are in reality a Metric thread.
    THEN, we come into this 55 degree/60 degree madness.
  8. NCsmitty

    NCsmitty Well-Known Member

    Mauser threads that I work with are geared for Threads Per Inch, 12 TPI actually, in both German style large ring and small ring Mauser actions. There are other threads used but the majority is 12 TPI.

  9. Clark

    Clark Well-Known Member

    I have shot Mausers with the barrel tightened finger tight, 100 foot pounds of torque, and 1000 foot pounds of torque [requires a long cheater bar and a beer belly].

    I can't see any difference in accuracy, so I do 100 foot pounds, so the barrel will not fall off.
  10. dirtyjim

    dirtyjim Well-Known Member

    mauser barrel threads are and always have been 12tpi, not metric.
    at the time they were developed the mauser bros. were using british machinery that was not set up to cut metric threads. mosin barrel threads are also not metric.

    the thread od & id on mauser barrels and receivers varies quite a bit due to tolerance stacking. i can pull a barrel from one receiver then pull 5 or 6 receivers from my stash and the barrel will thread all the way in some of them by hand and not even start in others.
    as far as the 55&60° threads go i grind my own threading bits and i haven't noticed any difference between in fit on a barrel thats threaded 60° compared to one thats threaded 55°. if i'm going to chase the threads in the receiver they will be cut to 60°.
    getting the barrel properly dialed in the lathe is much more important than a couple of degrees on the threading tool imho
  11. Zeke/PA

    Zeke/PA Well-Known Member

    A 12 TPI thread pitch is close enough to 2mm that a U.S./English lathe won't know the difference in a short lead such as one encounters on barrel shank.
    Small Ring Mauser shank dia. .980/25 mm
    Large Ring Mauser shank dia. 1.100/28mm
    Last edited: Feb 9, 2012
  12. morcey2

    morcey2 Well-Known Member

    I thought it was 95040 TPF?

    Minor riddle there. I'm sure someone will figure out what that is. :)

    I just wanted to install the barrel to make sure that everything was correct, not to prepare it for shooting.

  13. Old Dog Man

    Old Dog Man Well-Known Member

    Mauser Barrel threads

    Hey there dirtyjim I'm located in Texas City, almost neighbors. I've retired and am selling my shop equipment (eventully) and have customer's asking where they can take their guns now that i'm not doing that anymore. E-mail me some info. on how to contact you. (albaker1937@yahoo.com) maybe I can send some work your way.

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