Martini in 40-70 SS 408-405

[andym79]

Hi guys, I was thinking about doing a martini in 40-70 sharps straight, has anyone done this or something similar?

My concern is about the length, will it make it around the turn, the case is 2.5" long.

Its basically a 408 calibre version of the 405 Winchester but predates it so you could say that the 405 Winchester is actually the 40-70 SS in 411.

I would really like to hear from anyone who has done one in something like 45-90, 50-90, 40-82, 405, 9.3x74r (though I think that would be too long) and if they make the turn okay?

Thanks

[marlinman93]

Which Martini action? If it's a full size there shouldn't be any issues. If it's a Cadet, or similar sized actions it might not work, or might require some relief to the top of the block.
I own numerous .40-70SS and .40-70 Ballard chambered guns. That's a great cartridge, and about .10" shorter than the .405 Win. One of mine was relined by John Taylor and he cut the chamber and rim recess so I could use shortened .405 Hornady brass in it. It's an original Hepburn .40-70SS, but now is much better with the modifications to use brass and not rework it.
Just too bad Hornady doesn't make the brass anymore! You might want to check availability of donor brass before committing to building a .40-70SS. A better choice would be .40-50SS and it would fit in any Martini action. Brass is made easily from .303 British, and it's super available, and cheap! Just need a set of dies and you're good to go.
I have two Rolling Blocks in .40-50SS and it's a fantastic smokeless powder round. A bit anemic with 50 grs. of BP though, so I used .38-55 data, and a RCBS CSA 300 gr. bullet.

[EDG]

Just measure your parts and cut out paper profiles.
Tape the paper breech block profile over the paper receiver and barrel stub cut out.
Then see if a paper cartridge will turn the corner.

Alternatively you could accurately draw the breech block, receiver and cartridge at 10X or 100X times full scale and check it.
Of course anyone with a CAD program could do it.

There is a free ware CAD program on the net for linux users if you want to try it.

[marlinman93]

Could you please send some pics of them? I'm curious to see :)

Pics of what? The guns? Bullets? .40-50SS ammo?????

[John Taylor]

I think there are about ten different 40-70 chamber reamers with the 40-72 also fitting in there. The difference between a 40-72 and a 405 is the bullet diameter, both use the same brass. I did my Phoenix in 40-50 SS but have not made any ammo yet to check it out. The cadet action may not work, even with the 40-50. I did one a while back in 357 Max and had to take quite a bit off the breach block.

[andym79]

The action is a large on I guess it was originally a 450-577, but was re done at the armory into 303 British!

[BigEyeBob]

A friend of mine has just finished a large frame in 557 x2- 1/2 " nitro express ,I 'm pretty sure with out mods to the breech block .

[Stephen Cohen]

The action is a large on I guess it was originally a 450-577, but was re done at the armory into 303 British!

I did mine in 45/70 so you will have no problem, since yours was also a 303 at some time the firing pin has already been sorted. regards Stephen

[John in PA]

.40-70 SBN would be a better bet in the Martini action. .45-70 definitely will fit, and the .40-70 SBN is only slightly longer, but better suited to the Martini and Peabody style breech.

[Reverend Al]

I suspect it would work with the cartridges you're suggesting. I spotted this large action Martini in an online auction recently and was sorely tempted to bid on it since I have RCBS dies for the cartridge, but it was bid up higher than I was willing to pay so I managed to resist it. It was an F. Grunder large action Martini in .38-56 Winchester ... (neat claw mount setup with a German scope too) ...

https://i.imgur.com/3KfyHkP.jpg