Converting a Martini Henry to .45/70 - no doubt insanely expensive

[fat tony]

Does anyone have any information on the feasability of converting a Martini-Henry to .45/70? - they way I'm thinking is it probably does not make any economic sense, but then having anything better than a Dodge Neon (1st generation) to get your arse around town also 'does not make sense' - I'm probably better off getting something already in .45/70, but up here in Canada there are advantages to having firearms that are off the books due to their antique status.  - I would not destroy a pristine full wood military example (not Nepalese), but put out feelers for a 'bubba'd' example with the forestock radically cut down & possibly shot out barrel. - or maybe I should just get a Pedersoli trap door & save myself some $, but have it 'on the books'. 

[bubba.50]

pretty much a straightforward re-barreling job. if it's 577/450 extractor will have to be built-up then ground to fit. if it's .303 it will have to be opened up for cartridge rim. other than that, just depends on how far you want to go on sights/stock. for what it's worth, bubba.

[John Traveler]

I remember talking with a former Queens Cup Canadian High Power Rifle champion about this very subject.

He stated that there was a Canadian source for machined chamber adapters that would hold and fire .45-70 cartridges in the .450-577 M-H chamber. The chamber adapter and fired case would then be extracted and reloaded for the next shot.  I first saw mention of this in an American Rifle magazine article about the national competitions at Connaught Ranges west of Ottawa.  A couple of good friends, retired Canadian Forces weapons technician types are connected to all aspects of the shooting sports in Canada.  I can ask them what the chamber adapter source is.

There is a proviso though.  The standard .450-577 bore is somewhat larger than the standard .45-70 bore, and accuracy MAY suffer.

Rebarreling, of course is the most appropriate course, but also the most expensive.

[longcaribiner]

The barrel shank threads are a standard English thread, very similar to SAE threads.  Same number per inch, just difference angle cut.   And the extractor can be built up rather easily.  Keep in mind that the Martini has no exposed hammer so competition in BP Sillywets is limited. 

I toyed with the idea of rebarreling a Martini to a 577 Snider.  That way the extractor can stay the same.  Hard to find a reamer though. 

Unless you are grossly enamored with the Martini, it may be cheaper to find a junk rolling block to convert.