Re-barreling the Yugo 48 Mauser Using a ShopSmith Multi-Purpose Power Tool

By Dennis Sandoz, GCA Silver Member

Two Yugo Model 48 Mauser rifles with original barrels had found their way into my gun safe. Unfortunately, they both had bad barrels, evidenced by visual inspection and a 50 yard group (pattern?) size in excess of 12 inches with iron sights. The only lathe in my home shop is a ShopSmith Model 10ER manufactured in 1952 so I decided to modify it to be able to cut metal and enable the fitting of two new fully chambered barrels to the existing actions.

Fortunately for this project a cargo container of original replacement barrels manufactured by Zastava in Kragujevac, Serbia, during the 1960s, was imported into the USA during 2012. I was able to purchase two of these new barrels with the original military contour for a total of $80. This was my first barrel fitting project so I made a number of phone calls to Jack Landis for technical advice as the project progressed.

The Barrel Vise and Action Wrench used in this project were purchased from Brownells (catalog part numbers 080-860-205 and 080-800-098, respectively). The only other tool I needed was a cheater bar to remove one of the actions. An old piece of galvanized pipe served admirably and this step of the project was routine.

The Yugo 48 Mauser action on the mandrel showing the ShopSmith setup to true the front of the receiver. Cutter inadvertently set on side for photo, receiver faced with tool rotated 6 90º to left.

Truing the front of the receiver was accomplished with the mandrel purchased from Brownells (catalog number 080-098-001). In the picture on the left below you can see the set up with the ShopSmith used for this step of the project. Converting the ShopSmith wood lathe for metal applications involved mounting a Harbor Freight 6″ Cross-Slide Vise on a steel plate clamped to the ShopSmith carriage and the purchase of a mini-lathe tool post and cutting tool set.

I made a fixture from a piece of scrap angle iron to hold the action in my bench vise for lapping the bolt lugs. Brownells catalog number 080-097-198 Bolt Lapping Tool set for the Large Ring Mauser was used with 600 grit lapping compound to obtain about 80% engagement on each lug.

Mauser Receiver Fixture for holding an action in the vise during bolt lug lapping. The screws shown are replaced with the action screws when using the fixture.

The next step was to assemble the barrel and receiver and check the headspace. One thing many people are not aware of is that in 1980 the specification for the 8mm Mauser chamber shoulder angle changed. When you order a new headspace gauge today it is made to the current specification which is not appropriate for a rifle made to the old specification such as a WW I or II Mauser or the new barrels I purchased that were made in about 1960.

The old specification drawing is very hard to obtain so I have included both drawings here for reference. (CLICK HERE to download these full size drawing as a pdf file. The page size is 8-1/2 by 11 inches so you can easily print and keep this reference. — editor)

The first rifle I assembled had acceptable headspace without any additional machine work! This is pretty rare but with a Mauser action three things need to match up so I still had some machine work to do. When fitting a barrel to a Mauser action it is necessary to have the breech end of the barrel hand tight against the internal receiver ring with a 0.002″ gap between the front of the receiver and the barrel shoulder. This needs to be accomplished in addition to acceptable headspace.

After careful measurement and consulting my ‘go to’ expert I concluded that I was about 0.003″ out of specification and needed to remove about this amount from the end of the barrel where it butts against the internal ring in the receiver.

The question was how to accomplish this with the equipment and tools on hand. I decided to use my ShopSmith and a very fine file to accomplish this task.

The setup with the breech end of the barrel supported by the lathe tail stock containing a copper bushing.

The breech end of the barrel was supported by the lathe tail stock containing a copper pipe fitting packed with grease that was used as a bushing to center the barrel in the tail stock and not ruin the barrel finish. A dial indicator was mounted in a vise to center the barrel muzzle in the 4 jaw chuck.

Note the aluminum “L” pieces I made to protect the surface of the barrel from the steel chuck jaws. I figured out later that a wrap of aluminum cut with scissors from a soft drink or beer can would have worked just as well and required fewer hands.

Next, I put the barrel in the barrel vise and tightened the receiver so that the 0.002″ gap between the front of the receiver and the barrel ring disappeared. This 0.002″ of crush is the specified tightening torque for the barrel to the receiver.

The barrel in the vise fitted to the action.

The next step is to mark the location of the extractor slot that must be cut in the breech end of the barrel.

ShopSmith setup for milling the extractor cut.

Now I was ready to mark the extractor slot location and mill out the slot.

View from the rear of the action, minus the bolt, showing the extractor slot.

The Harbor Freight Cross-Slide vise worked very well for milling the extractor slot. I simply unbolted the barrel vise from the bench and clamped it in the cross slide vise. I set up the ShopSmith with its drill chuck and used an end mill bit. Using a 7/16″ or ó” cutter would allow the work piece to be shimmed vertically just once.

The photo above shows my Yugo 48 project rifle with a Karsten adjustable cheek rest installed. The only things left to do are install a recoil pad and apply a finish to the new barrel. I fired a total of 10 rounds to completely sight in the new scope at 50 yards. The target below includes the last 5 rounds.

The center to center group size for five rounds is 0.675,” for four rounds the distance is 0.360″ and for three rounds the distance is 0.281″. Not bad considering the rifle at this time still had the standard military trigger, far from ideal with a trigger pull of 5.5 lbs.

© 2017 American Gunsmithing Institute. Reproduction of this article by any means without approval is not permitted.

7 Responses to Re-barreling the Yugo 48 Mauser Using a ShopSmith Multi-Purpose Power Tool

  1. Thanks for the article Dennis,

    I do not have a metal-working lathe either, but like you, I have acquired a 1950s vintage ShopSmith. Your article reminds me to improvise, adapt and overcome with the resources I have on hand and not cripple my imagination with self-imposed limits. As you’ve shown, with some thought and planning, improvising does not mean poor quality. Thank you for the reminder and inspiration.

  2. You are clever… Very impressed! Loved the part about the dial caliper in the vice to center the barrel muzzle in the 4 jaw chuck.. Awesome article! Thanks for sharing Dennis. Cheers Sir.

  3. Comments by the Author:

    For anyone wanting to adapt their Shopsmith Multi-Purpose Power tool for cutting metal I have created a 2nd generation design that offers several significant advantages compared to the first generation design included in the article. I would be happy to email to anyone interested a description of my 2nd generation design.

    • Could you send me your info on Shopsmith conversion to metal cutting I just happen to know of a old Shopsmith for sale.

  4. Would you please send me your info on Shopsmith conversion to metal cutting?? I own a 520 Model Shopsmith & no metal lathe. This info could be really helpful in filling a gap of not being able to work on metal.

    Thank you very much.

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