• This topic has 3 replies, 1 voice, and was last updated 4 years ago by Reg.
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    • #31382
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      Is it feasible to convert a Trapdoor to .357 mag? Would the pressure be too high even with the modern insert?

      I have a TD barreled action that someone buggerd the chamber and was wondering what to do with it. Someone attempted to drill at the rim and put a good size divot in it.
      I could have it tig welded and ream the chamber back to 45-70 but just wondered if I could do something a bit different.

    • #31388
      • Gold
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      It’s feasible, but care would need to be taken concerning chamber pressure.
      As with all conversions in all rifles, the darn extractor is often the biggest hurtle to get over, and inexpect this will be a case in point.

    • #31390
      • Bronze
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      I thought about the extractor too. Trying to make one that would function with the reduced diameter rim of the .357 may be more effort than it’s worth…
      Not being set up with machine tools, except a cheap little drill press and Dermal tool, makes it even that much harder. I was hoping someone had already did a conversion so I could get an idea how to modify the action and get a pattern for the extractor. I’m not confident enough at the moment to try winging it on my own… yet!
      With enough time I’ve been able to make a couple custom parts by hand for other firearms that work quite well. It was a lot of trial and error though.

    • #31394
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      You might be very careful TIG welding and trying to ream that chamber back to the 45-70.
      While the steel used in those barrels was what we now consider a mild or low carbon steel the steel was not made with the precision that todays steels are.
      Pockets or inclusions of various things often do strange things when brought to a high heat. Getting extremely hard and becoming unworkable is one of them.
      If it were to develop a hard spot at the weld then of course you could very and I do mean very carefully use a small tipped grinder and restore the correct dimensions but you will still have that hard spot and that would work as a stress riser and under pressure allow the rifle to burst upon firing.
      With some looking I bet you could come up with a proper replacement barrel if you wished to stay in 45-70 and there are those out there that have put in other black powder era cartridges.
      Rebarreling , especially with the 1873 Springfield action is really not a good place to get started in rebarreling. If you want to get into it, read plenty and start with a good 98 Mauser type action.
      The .357 Mag is doable and so is the extractor but it will require a lot of cutting and fitting. I can see it as a extractor not as a ejector.

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