Stock Wrist Crack Repair: Step by Step

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I will be shooting this one, a Reising M50 submachine gun, once the final NFA approval arrives. But meanwhile, the registered owner has allowed me to take the stock for the necessary repair work for a crack in the wrist.

My goal was to preserve the outward appearance of the stock (it's really quite nice), without utilizing crosspins, but performing a strong and permanent repair which would allow me to fire the gun without doing further damage.

I had never attempted a stock repair of this magnitude, but I was confident that I could gather the proper materials to have on hand for performing the time sensitive task.

Following are a few pics of the stock/crack before repair. It appeared on top of the stock wrist only, about 3-3/4" in length. And although there is a shadow for the stock inletting picture, the crack protruded downward approximately 1" at the rearmost inletting.








The Repair


To begin, I went ahead with an epoxy/dowel repair, learning as I went along. I did make what will be a very serviceable repair, but also made a critical error which will be explained later.

1. I selected a 5/16" dowel, and purchased a decent wood clamp and long shank 5/16" drill bit.





2. With the stock clamped to close the crack, I began with a smaller 3/16" bit which enabled me to better locate a starter hole for the larger bit.






3. To ensure proper depth for drilling, the tool bit was placed along side for the length of the crack, and marked with a piece of tape. As the crack emanated from the center of the stock at the rearmost inletting, and traveled rearward and slightly to the right, I needed to use my best judgement when drilling to follow the wrist and crack angles, and without breaching the exterior of the stock. Drilling was performed with the clamp in place, and to the depth which was marked on the drill bit. Compressed air evacuated the sawdust from the hole.







4. The crack could then be prepped for optimal adhesion of the epoxy by cleaning any interior oils/grime with acetone. With the clamp released, I used a medicine syringe for application, and then an empty syringe to force air into the crack for drying. The application of fast evaporating acetone revealed the full length of the crack, as it stayed wet for a little longer inside the crack.







5. The stock could then be prepped to prevent a mess. I used general blue painter's tape to mask around the crack. I applied a coat of paste wax to the exposed area, using a q-tip with the cotton swab removed, so no excess paste wax would be forced into the crack. The dowel was inserted fully (dry), marked and removed to ensure the proper depth of insertion, and corresponded closely to the drill bit depth.









5. The epoxy was then mixed. I chose a marine epoxy with a 60 min. set up. This allowed for more working time and better flow when filling the crack. A longer curing time also produces a stronger compound. An epoxy with a short set up time will begin curing to quickly to properly flow. The stock was then 'warmed up' with a hair drier to also aid with the epoxy flow. I pulled the cotton swab off another q-tip to use as an applicator to fill into the hole.

The amount of epoxy which I used would be very difficult to measure, such as in milliliters. But suffice to say that the total glob was just about the size of a small grape.









Here is where I made a rookie mistake which affected aesthetics. I had drilled a 5/16" hole and used a 5/16" dowel. I neglected to account for the thin film of epoxy which would surround the dowel when inserted, and upon reapplying the clamp, the crack would not fully close. Next time, I will lightly sand the dowel to diminish the diameter - just enough so that clamping would close the crack more tightly.

6. The dowel was then inserted, acting as a piston and forcing the epoxy to evacuate the drilled hole, and flow into the crack. As the epoxy is somewhat thick, it built up a hydraulic pressure, and the final 1/2" of dowel insertion needed some assistance with a hammer, stopping when it reached the depth mark on the dowel. The clamp was then reapplied.









7. While the excess epoxy was oozing from the crack, I simply wiped it away with a cloth, and kept wiping for about twenty minutes, until it stopped oozing. Then, whether it made a difference or not, I just rubbed some of the sawdust over the crack, penetrating only the outermost exposed compound. The entire project was then allowed to rest for 2-3 hours








8. After allowing plenty of time for the epoxy to initially set, the masking tape was removed. The acetone came in handy again to soften and remove an epoxy finger print smudge which I didn't see earlier. A small amount of the epoxy which worked its way under the tape near the insertion point was CAREFULLY chipped away with the edge of my pocket knife. Walnut stain was then applied to the exposed epoxy/sawdust layer. And the then the project was allowed 24 hrs to fully cure, while still clamped.

Had I slightly diminished the diameter of the dowel before insertion, I would bet that the repair would be barely visible. But as it stands, the repair is done, and likely quite strong. I will need to mate the submachine gun action with the stock to perform enough relief by removing just enough wood at the rear stock inletting, so that the rear trigger housing lug will not contact the stock when firing and cause another crack.







9. The clamp was removed, and the entire area buffed with a cloth. Again, not perfect, but plenty serviceable now.

Thanks for looking on!



 
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Nice tutorial. I've had a stock or two (SKS, Type 53) that had similar cracks, but I didn't think they were worth saving. I'll have to see if I still have them kicking around and try this for practice.
 
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Some follow-up on the above:

To complete the project, it was necessary to eliminate the conditions which caused the crack in the stock wrist. The main cause was movement or play in the stock lug region. To illustrate, the following pictures shows the two recoil lugs on the gun action. The main recoil lug is on the rear (right in first picture), and there is a rebound lug on the front of the action (left in first picture). The second picture shows the rear of the main recoil lug.

When the action was place inside the stock without tightening the action screw, the receiver of the gun could move approximately 1/16" forward and backward. This looseness allowed the rear trigger housing lug to be able to contact the stock inletting at the rear, and eventually precipitate the conditions for cracking.







The next pictures illustrate the stock inletting areas for the rear and forward lugs. You will notice an extremely crude, temporary, but entirely effective fix which allowed me to take the gun to the range, and shoot without any concern for causing further damage to the wrist area.

I simply found a 1/16" thick piece of coated cardboard packaging and cut a shim to fit behind the rear lug. This shim entirely eliminated the back and forth play for the action inside the stock. I fired a total of 42 rounds with no issues. One day, I might address this shim issue with something more sophisticated, but for now, it works quite well.







For a little insurance, I also lightly filed the rear inletting area, which now includes the end of the dowel which was inserted for the repair. Since the shim at the recoil lug had moved the entire action forward, I did not remove much material.

Just a note. After dressing the area, I did apply walnut stain. I noticed that the birch hardwood dowel accepted the stain quite well. But the epoxy which had dried for 72 hours was not as receptive to stain as it was in the first 2-3 hours of application. I may attempt the stain in this area again, and maybe not. It is not an area which is visible when the gun is assembled, and the visible epoxy is a good indicator that the wrist crack problem has been addressed. Potential future owners of this Reising M50 might appreciate the clue which is left for them inside the inletting.







Finally, with the masking tape, acetone application, wiping of the excess epoxy, and general clean up, the original stock finish did suffer and had become a little dull. Normally, I don't address finish issues just to make a gun pretty. But I did want the gun's finish to appear consistent at project's end.

Without getting carried away, I applied a small amount of the walnut stain, and blended into the dulled areas with a cloth, and finished the same areas with a light application of BLO, buffing with a dry cloth as it cured. Not too shiny, not too dull. And from a two foot distance, the repair is hardly visible at all.







Conclusion:

I think it is prudent to cover an important point, here. This was a Restoration project. The purpose was to reclaim the utility of an otherwise non-viable firearm - without any attempt to upgrade any of its functions, or to enhance its outward appearance. Restoration practices may incorporate conservative repairs of existing parts, or even the replacement of broken or non-serviceable parts with period correct and model specific parts - avoiding reproduction parts whenever possible, but understanding that most arsenals have discontinued production of our precious artifacts. Firearm restoration processes should not turn into into wholesale refinishing projects to make the gun pretty or better - but instead to correct deficiencies while preserving the historical essence.

There is a fine line between restoration and refinishing, and one should continually weigh the consequences of each step along the way by asking a simple question, "Is this necessary to the preservation of the firearm, or am I trying to enhance its function or appearance?" If the question may be answered satisfactorily, then it becomes much easier to keep from crossing that line.

I hope the above project might offer the step by step documentation of a restoration process, that others might benefit, and a broken warhorse or two might be returned to their former intended function and glory. Thank you.
 

greencobra

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Heck of a lot of work. Looks great.
yeah, for sure, super job on that. i'm going to try this on a beretta 682 stock someone gave me but then i never used because of a crack in pretty much the same location.....when i get ambitious sometime. good info, thanks for documenting it.
 
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