50-70 trapdoor re-barrel not working ????

Discussion in 'Gunsmithing and Repairs' started by wjls, Nov 20, 2021.

  1. wjls

    wjls Member

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    here's what's up,, removed an ok barrel from a nasty receiver (both nickel plated in poor shape). Cleaned and blued the barrel to match one of my 2 other nice looking receivers, and the thing screws past the alignment marks on one, and right on the mark with the other (both, hand tight). It all amounts to several thousands difference only between no good and a tight barrel. Is there a legitimate way to fix this. I know the gov. arsenal fix for an M-1 with a like condition is to roll the breach end to displace metal at the mating surface. Has anyone out there dealt with something similar on trapdoors ????
     
  2. BBBBill

    BBBBill Member

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    I don't know about trapdoors, but I've made breeching washers from shim stock for tightening a metric FAL that timed up too far. It's been working fine for 20+ years. I got the idea to try that because the Brit/Canadian/Aussie versions (so called inch pattern) use a breeching washer as a normal part of their build process. Probably something to do with machinery limitations used vs what FN/Steyr/et al used on the metric guns.
     
  3. wjls

    wjls Member

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    Thanks,, was thinking about that but am a little hesitant to do it, but will keep it in mind, now that I know it is done on others. It's irritating that the only receiver I have that fits is so damned ugly with flaked off nickel and rust.. I might even try to clean it up if all else fails, do a reverse plating on it and scrape off the rust.. but it will look like crap with all the pits in it..
    thanks again for the insite..........
     
  4. FROGO207

    FROGO207 Member

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    Clean it up, fill in the pits with red lead, sand and paint it with one of the new hard paints. Should last OK unless you treat it badly.
     
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  5. brickeyee

    brickeyee Member

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    Nothing wrong with a thin steel washer to set headspace correctly.

    My 1866 looks like it was exported, never used, and then imported back into the US.
    The rifling is perfect and it is very accurate.
     
  6. wjls

    wjls Member

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    thought about that too,, still wondering and looking for input before I do anything I might regret.. a .003 washer is awful skinny but It might be the winner in this scenario...
     
  7. BBBBill

    BBBBill Member

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    As noted, I use stainless shim stock to make what amounts to a washer. Finding a pre-made washer of the correct thickness might be problematic, but you could have a machine shop surface grind one to your desired thickness. Cheaper to get some shim stock and use shears or a utility knife to cut one out. You can calculate the needed thickness fairly easily if you know the thread pitch and how far the barrel turns up now.
     
  8. wjls

    wjls Member

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    yep,, working on that aspect right now,, but just for reference if your looking for shim stock,, I'm going to check my harley parts, cam shims for iron head sportsters just might be the cat's meow for this,, .
     
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