Martini Henry Re-Barreling?

Drachenblut

Drachenblut

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Hello Gents,

I have heard rumors for many years now of people taking the classic military Martini Henry or Martini Enfield and re-barreling/re-chambering it into some very hefty calibers (one gentleman mentioned .375 H&H!, another 45/70 Gov!)

I wanted to know if this is total bonfire beer talk, or if the Martini Henry or Martini Enfield actions are strong enough to handle this kind of conversion work? I understand the original Martini Henry round had something like 75 grains of black powder behind it.

I look forward to hearing about this being cleared up,
Yours,
D
 
They are a pretty sturdy action but there is a limit to how far I would push one with modern cartridges.

My father bought one that had cracks around the block pivot pin. Came with no barrel so don't know what was on. He repaired it and had it chambered to 32-40 for BP.
 
375 H&H on this action would be "bon fire beer talk"... way too much pressure if loaded to nominal H&H loadings.

Anything based on an old black powder cartridge will be fine provided the action is in good shape. (ie. 45-70, 38-55, 32-40 etc.) 303 British is popular in those actions as well.
 
Thanks for the information gentlemen. It would seem that an old black powder cartridge with smokeless loading might be a good idea... what would you think of 50-110? Too strong? I am merely thinking how difficult it is to get/make .577/450 brass and load for it. Exactly what size bullet would one have to use, and does it have to be just lead? What about grainage?
 
The potential problem with the 50-110 could be the length of the cartridge. The cartridge needs to go 'around the corner' when it is fed into the chamber, as the feed ramp is curved. If the cartridge is too long, and or the cartridge is too large in diameter, it cannot get around the corner. That is why I suspect the talk of .375 H&H is a bit wrong, as it is long. I know that one person who chambered their Martini for .45-70 had to be careful about the length of cast bullet that he used, as too long of a bullet, and too long of a cartridge overall length, would not feed.
 
I hear that the 577/450 is not bad to load, I've been collecting some components for doing so but the but rebarrelling to 45-70 is tempting. I've got a nice mkIII that I wouldn't rebarrel but the mkIV is sort of tempting to rebarrel. How criminal would it be to rebarrel an molested mkIV?
 
577/450 is pretty easy to reload, the biggest thing is a properly sized bullet. The mark IV should take somewhere in the range of .470-.472. Once that's taken care of it can be reloaded without dies. That's usually what I do. I use a paper patch bullet that's held in by neck tension. No resizing means excellent case life. At $4 a case, I want all the case life I can get.

Talk to ellwood epps for cases. Dies can be ordered from lkee factory sales. All you really need though is the shellholder for priming.

J
 
For the record, I am reading through those papers... interesting. I keep noting that the Martini Enfield has a case hardened breech block. What does this mean, and do Martini-Henry's not have this?
 
HeadDamage said:
I hear that the 577/450 is not bad to load, I've been collecting some components for doing so but the but rebarrelling to 45-70 is tempting. I've got a nice mkIII that I wouldn't rebarrel but the mkIV is sort of tempting to rebarrel. How criminal would it be to rebarrel an molested mkIV?
Click to expand...

577-450 is easy to reload,

Lee makes dies for it, they are the large dies 1" not 3/4" so you need a proper press.

Brass I use jamison brass, Mystic precision, Jerry told me he can get more if I need some, but its not cheap

bullets I use 405grain cast that is the same as 45-70

and I'm using imr4227 smokeless powder :eek:
 
Excellent. Woodchopper, could you PM me with a list of what dies/press you use, where you bought it (where I might be able too), where I could get this Jamison brass, and where I can get the 405 cast bullets? What is your load for the IMR 4227 powder, your case length/overall length? I would love to find a single, good reliable load and this sounds like a good place to start, as everyone else seems to insist on using black powder, which I would prefer not to deal with.
 
Drachenblut said:
For the record, I am reading through those papers... interesting. I keep noting that the Martini Enfield has a case hardened breech block. What does this mean, and do Martini-Henry's not have this?
Click to expand...

It means that it was made of mild steel then heated red hot in the presence of carbon until the surface absorbed carbon to a depth of .003 - .005" roughly. When quenched into water that left the surface very hard but the inside soft so that it did not shatter.
For smokeless loads you would be wise to bush the firing pin because many of these guns had large tipped firing pins which potentially would allow primers to burst.
I can't see why you would want a 50-140 cartridge --- I had a 45-120 for a while and it kicked like a mule. Most of the people I know who have had such cartridges got rid of their guns after a relatively short time because they just were not fun to shoot. I also would doubt that you could load a 45-120 into a Martini because of the length. The 450-577 loads because it has a fat base and the large opening for the back of the chamber allows the cartridge to go in at an angle for a bit before flattening out and traveling forward on the level.

cheers mooncoon
 
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The M-E had its firing pin reduced in diameter. Large diameter black powder firing pins can result in blown primers with higher pressure smokeless loads.
A dovetailed piece was fitted across the blockface, a smaller hole drilled, and the firing pin altered. A modern conversion would likely involve a threaded bushing being fitted, drilled and faced.
Extractor alterations are needed too.
These conversions have been made for years, the procedures are pretty much worked out.
 
Drachenblut said:
Excellent. Woodchopper, could you PM me with a list of what dies/press you use, where you bought it (where I might be able too), where I could get this Jamison brass, and where I can get the 405 cast bullets? What is your load for the IMR 4227 powder, your case length/overall length? I would love to find a single, good reliable load and this sounds like a good place to start, as everyone else seems to insist on using black powder, which I would prefer not to deal with.
Click to expand...

PM sent

Oh and I see your just down the road from me
 
Drachenblut said:
Just curious, if I were to rechamber a Martini into 45-70 Gov., would I need to replace the barrel?
Click to expand...

Absolutely. The chamber on a M-H is a nominal .577 at the base. The chamber on a 45-70 is .505 at the base. That's without going into bore size differences.

If you want to shoot 45-70 in a M-H you MIGHT be able to get away with a chamber adapter.

J
 
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