Case head protrusion 98 Mauser question?

Discussion in 'Gunsmithing' started by Shawn.54, Oct 2, 2017.

  1. Shawn.54

    Shawn.54 AH Fanatic

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    I’m building a Mauser 98 and was wondering what proper amount of case head protrusion was acceptable.
    The distance from barrel face to bolt face.
    Shawn
     

  2. Clayton

    Clayton AH Fanatic

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    Can't give you an answer right now. But it's going to have some variables to take into account: Cone Breach? Caliber? Belted or not?

    Glad you posted this one, I'm going to get to learn something from it.
     

  3. Shootist43

    Shootist43 AH ENABLER GOLD SUPPORTER AH Legend

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    As long as the barrel is properly head spaced is this really a concern? I'm not sure, but it seems like this is the "back end " of the same measurement. Either that or I'm about to learn something.
     

  4. Shawn.54

    Shawn.54 AH Fanatic

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    .404 Jeffery is the cartridge the bolt had some wear on the face so when I opened the bolt face I removed .002 -.003 to clean most of the wear marks you can still see a shadow of wear in the primer area so I think I did not take to much. Was just wondering if there was a tolerance, max min.
    Shawn
     

  5. Clayton

    Clayton AH Fanatic

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    AH! If you're NOT fitting a new barrel, that small amount shouldn't be a problem. You should still be well covered for the case web. If you are fitting a new barrel you will need to pay attention to this dimension. You do not want the web exposed back there. I can't find anything but SAAMI dimensions, and they're only for the loaded round dimensions. There's GOT to be some "smithing" data to tell you. As a guide you could work out the headspace dimension and figure a minimum clearance dimension. You could always remove a little more off the chamber face easier than to have to set back the whole barrel.

    Please excuse me if I'm telling you things you already know.
     

  6. Shawn.54

    Shawn.54 AH Fanatic

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    This is a new barrel and the bolt and action are not matching #s since the barrel is new I’m going to bump it forward a little.
    Get a good fit and that’s that.
    Shawn
     

  7. Clayton

    Clayton AH Fanatic

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    Good plan. You can always take off a little, but you can't put it back on. You ought to have a nice rig when you finish.

    Wish I could hang in the shop with you. You could teach me a lot. Made a lot of machine drawings for the shop over the years, but the only tool I ever put a hand to was a new LaBlond lathe I bought for them. LOL, as a project manager I furnished them with whatever they wanted, and they would do anything I ask. I had some neat stuff back when I shot benchrest.
     

  8. Shawn.54

    Shawn.54 AH Fanatic

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    Working in a machine shop does have its perks but the way this world is going it’s harder to do gun work I need to get my own equipment.
    Shawn
     

  9. Shawn.54

    Shawn.54 AH Fanatic

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    We do have an old LaBlond lathe but mostly Mazak CNC lathes and mills it’s a challenging job but also rewarding when you can say I made that.
     

  10. Cousin Bongo

    Cousin Bongo AH Member

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    Depending on the 98 bolt type installed, the ejector guide slot face/tip/end-to-barrel or extractor-to-barrel gap should be zero or minimal - ideally the guide slot end or extractor should almost (or even just barely) touch the barrel face. Closer is better. From here on I'll just call this the extractor-to-barrel gap. The case extractor groove is unsupported, but you should do things so as little of the case head as possible is unsupported...which is why we want the extractor-to-barrel gap to be zero or as close to zero as possible.

    When rebarreling a 98, the way I do it is to first check the bolt locking lugs to receiver locking shoulders for area of contact. You might have to lightly lap the bolt locking lugs to the action locking shoulders with a lapping tool - lapping only enough to get at least 75% - 80% contact on each lug while being careful not to break through the hardened surface of the action locking shoulders with too much lapping. (Doing so results in locking lugs set back, and many times claims of "soft" actions). Then, depending, I might true up the face of the receiver and possibly the face of the inner "C" collar (again lightly!). Next, I short chamber and install the barrel so that the barrel breach face contacts the inner "C" collar .001" to .002" (max) before the barrel shoulder - this is how Mauser designed it and with reason (be aware there are some "experts" out there who spout this isn't necessary...however, it's actually a safety thing and I tend to think Peter Paul Mauser knew a bit more about his design than they). I check the extractor-to-barrel gap and, if good to go, set final torque/headspace. Nebulous and perhaps I missed a step or two, but that's the quick condensed version.

    CB
     
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  11. Shawn.54

    Shawn.54 AH Fanatic

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    CB thanks a lot this was the basic plan I have and when it comes time to get serious I will refer back to this only thing I had not thought about was lapping the lugs what is the tool and where can I get one or can it be made.
    Shawn
     

  12. Cousin Bongo

    Cousin Bongo AH Member

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    Easiest to just do a web search for "Mauser bolt lapping tools" for info. You can buy or rent them, but I've made several from old worn out Mauser barrels - just need a lathe, a rod, a spring and a retainer (clip or pin, etc.). Easy really. What is does is put constant pressure on the bolt face while your working the bolt up & down with lapping compound on the contact surfaces. However, more often than not, I've found that the bearing surfaces are quite good and no lapping is needed.

    In my post above, that should have read: "the barrel breach face contacts the inner "C" collar .001" to .002" (max) before the barrel shoulder contacts the front face of the receiver." What Mauser wanted was a good tight fit/seal of the barrel on the inner "C" collar (gas handling and such).

    CB
     
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  13. Shawn.54

    Shawn.54 AH Fanatic

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    In my head I was making one looked on line at I’ll have one by weeks end.
    Thanks
    Shawn
     

  14. CAustin

    CAustin AH ENABLER BRONZE SUPPORTER AH Ambassador

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    Shawn any current pictures of your project to share?
     

  15. Shawn.54

    Shawn.54 AH Fanatic

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    Just a collection of parts and I ordered brass today going to send for gages and reamer in two weeks starting on a back sight (peep) next week. Bottom metal, action are inlet barrel about 85-90% I have a stub I turned on a lathe with lose thread that I can turn in and out of action by hand that I used to inlet barrel. The stub is going to be turned into a lapping tool for locking lugs.
    All I need is time now which is hard to find.
    Shawn F5818F54-B1FE-419C-8795-F367E58F3069.jpeg
     
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  16. CAustin

    CAustin AH ENABLER BRONZE SUPPORTER AH Ambassador

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    Well your making progress brother!
     

  17. Clayton

    Clayton AH Fanatic

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    Quality takes time. No need to rush now and regret later.
     

  18. mdwest

    mdwest AH Elite

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    Looking pretty awesome Shawn.

    youre making me jealous for sure.. the biggest thing I ever owned prior to a year ago was a 45-70... then I picked up the big bore gateway drug (375HH).. and now all of a sudden I find myself wanting a 404J or a 416 rigby.. not sure why.. I cant think of anything I have any interest in hunting that requires anything more than the 375...

    but I sure do get green with envy every time I see a new 404 or 416 post pop up lately lol..
     

  19. Shawn.54

    Shawn.54 AH Fanatic

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    I mentioned in the PM that I had a 35 Whelen that I gave my son well to replace it cheaply I got a 375 Ruger in a Mossberg Patriot rifle I fell in love with the cartridge and figured if the Mossberg could hold a 2” group at a hundred yards I’d be happy well it can print a 1/2” group if I do my job. But it turned into my gateway drug hence the 404J which my never see anything bigger than a black bear.
    Shawn
     

  20. Shawn.54

    Shawn.54 AH Fanatic

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    Yes I’m not going to rush it and I just found out that a buddy at work just purchased a checkering kit and said I can use first and teach him after.
    Shawn
    Glad you’re back.
     

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