What to do with Yugo M48 Mauser?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by goose, Jun 30, 2010.

  1. goose

    goose Well-Known Member

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    I have an M48 mauser with a rusty barrel. I've seen some info in sporterizing and I would probably go with something in the 308 family. I know starting with another type of action may be cheaper/easier. I would like to know what all should be done to the action itself other than drill and tap for scope mounts.

    Considering the parts available and the nature of the action, would it be better suited for a lighter/shorter walking around rifle, or heavy varmint type?
     
  2. benchracer

    benchracer Well-Known Member

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    In addition to drill and tap for scope mounts, I would recommend the following:

    1. Lap the bolt lugs.

    2. Lightly true the bolt face.

    3. Square the barrel mating surfaces on the front of the action (there are two).

    4. Have the stripper clip charging hump milled off (this makes it easier to find scope mounts that will fit your action).

    5. Either have the existing bolt handle re-shaped for scope clearance or have a new bolt handle welded on. Even though the existing bolt handle is of the bent type, it was not designed for scope clearance and will not clear the ocular bell of most scopes unless the scope is mounted excessively high.

    6. Install low swing safety for scope clearance.

    7. Glass bed the action into the stock (pillar bed optional).

    8. Install aftermarket trigger.

    The M48 actions are slightly more complicated to re-barrel than a standard '98 mauser because the M48 design incorporates an extractor cut in the breechface of the barrel. The difference in cost is generally pretty minor.

    The mauser actions are considered to be less rigid than the tube type actions common among rifles of more recent design (ex. Remington 700, Savage 110, etc.). It is my understanding that the mauser actions tend to flex excessively when fitted with the large "stovepipe" bull barrels of the type common to benchrest competition.

    That said, I have experience with sporterized mausers that have varmint contour barrels (similar in profile and weight to a factory Remington Sendero barrel). The varmint contour barrels work very well with mauser actions. Of course, the thinner sporter barrels work well also. Finding a varmint type stock for an M48 might be a bit of a challenge, but there are ways to work around that.

    I am a big fan of the mauser type actions. Though they may have their limitations where benchrest type shooting is concerned, in my opinion, the mausers are without peer in a sporting/hunting rifle. The M48, in particular, deserves a lot more respect than it gets.

    Good luck with your project rifle!
     

  3. shortgrass

    shortgrass Well-Known Member

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    Do not lap the lugs and be extra careful if you true the bolt face! Mausers are made of LOW CARBON STEEL and are 'case' hardened. The 'Case Hardening' is at the most .015" thick, sometimes considerably less! If you lap the lugs you could lap thru the Case Hardening to the low carbon steel or make the 'hard' steel too thin and the bolt lugs will "set back" when the rifle is fired, ruining the receiver. Leupld makes a two piece base set that doesn't require the clip charger to be removed. Mausers make fine huntin' rifles and are "Classic" for that purpose.
     
  4. benchracer

    benchracer Well-Known Member

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    While the point that shortgrass makes regarding case hardening is well taken, I believe it is going overboard to advise against lapping the bolt lugs. There are many reputable gunsmiths who perform that very task on a routine basis.

    Though I am but a rank amateur, I have lapped the lugs and lightly polished the bolt face on several mauser actions with excellent results. Fifteen thousandths of case hardening doesn't sound like a lot, but is actually quite a lot of material to remove with nothing but abrasives and hand tools. Even using a carbide bit and a drill (as I have done while drilling and tapping for scope mounts), it takes a bit of work to get through the case hardening. By comparison, it generally takes very little material removal to get 75% contact on both locking lugs or to square the bolt face to the barrel threads.

    No gunsmithing task should be taken lightly or approached in a ham handed manner. The shooting sports in general, and gunsmithing in particular, pose inherent risks that must be managed by the application of common sense. If one does the homework necessary to understand the subject matter at hand, proceeds slowly and cautiously, and pays attention to what is being done quite a lot can be safely accomplished.

    Where the mauser actions are concerned, it pays to be cautious. There are indeed some mauser variants that have a reputation for being "soft" or for having very thin case hardening. Some of the WWI and earlier mausers and some of the 1943-45 German produced K98's are especially known for quality control problems related to metallurgy and heat treating.

    The M48's however, were never manufactured in factories being pressured by allied bombing or by slave labor. They are of high quality and are likely to be in much better condition than their wartime brethren.

    Having said all that, we must all act within our personal comfort zones. I would never advise pushing a gunsmith to perform work with which he is uncomfortable. I would, however, not hesitate to search for a gunsmith with whom I see eye-to-eye.

    In conversations like this, I am often reminded of something once said by late NASCAR great, Smokey Yunick, to the effect that many engineering "facts" turn out to be just someone's opinion when they are boiled down far enough.
     
    Last edited: Jul 2, 2010
  5. shortgrass

    shortgrass Well-Known Member

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    I've seen enough different Mauser actions with lugs set back or locking lugs beat out of shape that I won't even go there. And not just those made under 'war time pressure' or with a reputation for being soft. No sense in trying to turn a 'work horse' into a 'race horse'. If you check lug to surface contact before you lap you may find there is already 75% contact there. You just never really know how thick the case is. I've never known a Mauser '98 to fail to the point of being dangerous (like blowing a bolt out of a reaceiver) but I've seen many that are no longer useable. I've got quit a few sporters of my own built on '98s, they'll shoot 5/8" to 3/4" groups and the lugs were not lapped. That is quit good enough for a sporter IMO. If you need better accuracy than that, use a modern action made of alloy or stainless steel. just my 2 cents P.S. Hobbyists can do things that a business won't. Its called 'liability'.
     
  6. RT2506

    RT2506 Well-Known Member

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    Keep in mind that the Yugo 48 is not a true 98 Mauser action. It is a little shorter than the 98 Mauser action and it will not fit into a stock for the 98 Mauser. Boyds' does make a "JRS Cassic Stock" it is a laminated wood stock for the Yugo M48. They are the only ones I have see though.
     
  7. Coyboy

    Coyboy Well-Known Member

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    Do You duck hunt?






























    They make excellent decoy weightslightbulb
     
  8. goose

    goose Well-Known Member

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    Too bad, I don't duck hunt or fish.
     
  9. Jamie6.5

    Jamie6.5 Well-Known Member

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    When I asked my 'smith about accurizing my M98 he checked it for square and lightly touched up the barrel mounting surfaces.
    When I asked about lapping the lugs, he showed me the wear, pointed out how even it was and noted the serial numbers matched between the bolt and receiver.
    If you are putting in new/different bolt in a old/different receiver, fine then lap a little.
    If you aren't, check the mating wear with a little prussian blue or white lead(if you can find any). That will tell you if how much mating surface contact you have.

    Mine shoots lights out.
    YMMV.
     
  10. specweldtom

    specweldtom Well-Known Member

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    RT2506 mentioned that the Yugo large ring '98 is shorter than a standard '98 large ring. They should work fine on cartridges that are shorter than a .30-06 and that have .473" case heads, I wouldn't use one for a magnum cartridge or any modern high pressure cartridge that is designed for more than 55kpsi. No sense in pushing your luck.

    On metallurgy: I always thought the Mausers were through-hardened receivers and bolts. However, Parker Ackley has some info in one of his handbooks that states they are low to medium carbon forgings that are case hardened up to depths of .015" as shortgrass said. The case hardening must be for wear resistance, since the core metal has to have the strength and toughness to contain the chamber pressure spikes without yielding. The thin case hardened surface is very strong, but is so hard it can be brittle. It must be supported by the tougher (softer) core of the forging. Steels with 25 to 45 parts carbon (.25 - .45 %) will respond to quenching from case hardening temperatures. The higher the carbon content, the higher the hardness (strength) will be after quench. Unlike the carbon rich surface, they won't get hard enough to be brittle if the heat treat is done correctly. I don't know if Mauser or Zastava does a low draw after quenching, and Ackley didn't say either, but it would make sense to me to relax some of the peak stresses caused by the quench.

    My impression is that the post-war Yugo's and Zastava commercial Mausers (Mark X, Charles Daly, Whitworth) are good metallurgy, properly heat treated actions. No proof other than examining several of the MK X's and Whitworths that were massively over-pressured. Blown primers, stuck cases, gas cut bolt faces, etc. All had been chambered in modern belted magnum calibers. I don't have that experience with the 48's, but I already said I wouldn't chamber one in a Magnum caliber. The .473" diameter cartridges leave more barrel steel in the chamber than the magnum cases. Just extra insurance.

    I've drilled and tapped several large ring and small ring Mausers and one Yugo 48A. For whatever reason, none were a problem like the U.S. 1903-A3's that I've drilled and tapped, which were nothing but trouble. They and Garands and M-14's are all case hardened and the surfaces will turn a highspeed drill instantly. None of the Mausers have done that so far. The case is not as hard, or it's much thinner, or both.

    Truing the face and inner shoulder of the barrel seat won't hurt because they are not wear surfaces, and should only take .001" to .005" to clean up anyway. Bolt lug faces and recesses are wear surfaces, but should only require .001" or less to bring into 75% contact. I would do the barrel seat faces for sure, but lap the bolt lugs only if they need it (less than 75% contact).
    The Mauser actions have an ace in the hole. A 3rd safety lug. I've never personally seen one catch a bolt, but I like that it's there.

    Shortgrass makes a good point about liability. He has to set limits on things he's willing to do. To a lesser extent though, so does a hobbyist. For instance, I wouldn't touch anyone else's trigger, even to increase sear engagement or spring load. Too much liability for a hobbyist.

    Brownell's sells some very plain walnut sporter stocks made by "Wood Plus" for Yugo Mausers. Check them out.

    Hope this helps too. Good thread.

    Tom
     
  11. Coyboy

    Coyboy Well-Known Member

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    Alot of good info in this post.

    I have seen military Mausers that seemed soft and if case hardened, poorly done. HSS drill bits walked thru like butter when drilling scope base holes. I have also seen one front reciever ring crack thru when the original barrel was pulled. As shortgrass stated some are not worth the trouble and have shown severe lug abutment set-back. I no longer do them after a customer sent me one for rebarreling that had a reciever ring crack welded, and very nicly welded I must add. But the potential for failure in my mind is greater with these actions then todays comercial actions. I have no problem with the Mark X and comercial mauser clones. the nice part about these is most of the extra work that needs to be done to a military action is already complete, Bolt handle work. scope base holes, ect.

    Other than the nostalga of a reworked military mauser, You would be money ahead to buy a rem 798 and rebarrel.
     
  12. Clark

    Clark Well-Known Member

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    I have dozens of Mausers in various states of sporterization.
    I have been doing this for 45 years.

    It is like handloading, probably not cost effective, but it is what fanatics do.
     
  13. shortgrass

    shortgrass Well-Known Member

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    I'm not far behind you in years, Clark. Have fun, satisfy yourself with another of your creation. I grew-up watchin' Dad, Uncles, and most for their friends build rifles on Mausers and , sometimes, a Springfield. I've seen some extraordinary rifles built, virtually by hand (except the nessesary lathe work). I own many myself. My last hunting trip was with rifle built on a Steyr made '98... I, also, saw some fail, probobly for many different reasons. While I was attending 'smith school I did repairs for a local pawn shop, lots of repairs. Being close to a school like that there were alot of Mausers around, in various conditions I might add. Saw several more receivers with failures. Came back home, opened shop, I've seen one or two more. My observations and what I learned brought me here; Respect a Mauser for what it is. Know and understand the way it was made. Examine it closely before you build on it. Some Mausers are much better than others.