Converting a Greener Martini to a rimmed rifle cartridge

[jedman]

  I have a Greener Martini Mark III police shotgun in 12 ga.  I would like to convet it to a 45-70 based rifle.
 My question is, what extractor has been used in this conversion ? I know there are extractors for the 577-450 and the 303 Brit. but I am not sure of the different models of Martini frames and what parts would fit what frames.
  I assume you would have to recut the extractor fingers on the smaller 303 extractor or weld up and recut the 577-450 to work.
  I would like the advice from someone who is familiar with the conversion to 45-70 what is required to get a working extractor.
  I have E mailed Odin Arms who sells converted guns but they have not replyed and have been no help.
 I have included a pic of the 12 ga. extractor from my gun, maybe this will help.         Thanks,    Jed

[gunnut69]

I've not done one of these but since parts are difficult to find I'd weld up the existing extractor and cut for the new round, Is this the martini shotgun the Brits made to use a special round. If so it would not fire a standard 12 ga. shell. That would mean some serious mods to the breech block for the 45-70 to work..

[jedman]

    The breech block is no problem, It does not need to be modified except maybe bushed for a smaller diameter striker.  If you see the  U  shape of the extractor I have in the pic. If I were to weld "ears" onto the ends of the fingers it could be possible to modify the one I have to work.
  I would really appreciate if someone had a picture of there open breech showing the extractor used in a 45-70 conversion or even from a 303 Brit as it should be similar.
                                                                                              Thanks,  Jed

[Brithunter]

If your Greener has the little circlips to reatain the pin rather than the keeper screws then it's not a good idea to convert them. They are weaker than the screwed retained models.

[jedman]

         Heres a picture of my frame and the extractor I recently made.
  The frame is not the type with the circlips, I milled the extractor out of a piece of 4140 bar stock 1 1/2"dia.
 It is still uncut for the case rim as I dont have my barrel yet threaded, I need to rethread from metric 27 x 2.0 thread to 1.075 X 14, that is what the Greener frame thread is.
  The barrel I am fitting to it is a C Z 550 Safari barrel with a medium heavy profile that is chambered for 375 H & H mag. I have a shortened wildcat version on 45-100 brass that is about the maximum length cartridge that can be chambered with the block down.        Jed

[torpedoman]

I got my extractor from odin (50 bucks) have since found them as low as 20 check martini sites, there are several, and the single shot rifle ass. They were very prompt replying to me and i'm thinking of sending the gun to them for barrel work.