I'm looking for water volumes for different RIMMED cartridges to use for a .375 Cartridge.
I got one from William on the 356 tread:

In 1966 when the wildcats that were to become Winchesters Big Bore cartridges were just being worked up a fellow named Frank Hempstead very accurately predicted the performance levels of the new cartridges. Hempstead wanted the .375 caliber and spoke very authoritatively on its potential.
The .356 Winchester has approximately 59.8 grains of water to the case mouth and the same cartridge necked to .375 caliber with no other changes has an approximate water capacity of 60.8 grains of water.

This is a 37 Rimmed. I never seen or heard about it before. It looks like it could be blown out to receive a nice shoulder.
Then there is the 348 Win, that could be necked up and blown out. Don't know the volume.
I want to put this on a Martini Enfield, presently with a .303 Barrel!

I think I'd take a hard look at the .375 JDJ. A friend has one on an Encore carbine and it is a tack driver. I don't know the water capacity but, dies, brass, chamber reamers and even loaded rounds are available and that would save a lot of trouble and expense compared to a true wildcat. The .375 JDJ from a rifle has all the ballistics one could ever need and all the recoil I'd care to stand behind in a reasonably light rifle. The Martini action makes a fine rifle, though a bit of a problem to scope.

A whole lot depends on the rifle you plan on using.

If the regular 375 Win isn't enough thump. move up to the 375 JDJ.

If that's not enough for you (and not too much for the gun) then a 45-70 necked down would be impressive on both ends.

Or you could go the way of the 450 Hornady/Marlin and use a belted case. The 350 Rem Mag opened up is just one obvious choice.

The 375 Win is a straight wall case, I'm looking for a shoulder; somethng like the 375 JDJ. BUT, I'm also looking at the Rimm diameter and rimm to body relation.
I surmise, that a bigger Rimm diameter produces less backpressure on the action, since you spread the backpressure over a bigger area and a straighter case clings better to a dry chamber.

I looked at the following cartriges and the .348 and the 45-70 (Thanks Rocky for the idea, didn't think about it) and even the 45-90 might fit the bill; necked up or down to .375. The 375 RCBS might be a bit too long to fit easily in the Martini since the base cartridge is about 2 3/4". I think I can put any brass up to 2 1/2" into the Martini.

Cases here:

Have you considered the 444 Marlin case?

Ken Waters designed the .375 Express to save the original barrel on a classic Westley Richards rifle. This fine wildcat was based on the .444 Marlin and has a total water capacity of 64.5 grains of water and with a bullet seated .375” has a water capacity of 54.0 grains of water. You will probably not seat a bullet this deep on a single shot using spitzer bullets.

William
The JDJ has a rim diameter of .510 smaller then the .540 of the .303 (remember the Martini is in 303) and I'm looking for the same diameter or greater.
So, the 348 or the 375 Jurras would be the ticket, although the Jurras is a little short, and I wouldn't know where to get the brass from. Maybe I use a 28 Gauge Brass shotgun shell and neck it down... Well, maybe not.

I'm still looking, BUT I have a contender in the 348. It has a big rim to lower backpressure and the body is big enough to get a good shoulder in an Ackley Improved configuration.

What do you guys think??

Wolf

Would the 375 Flanged work? How 'bout the 375 Nitro Express 2 1/2", or even the 9.3x74R necked to 375?

The 375 Flanged can be seen at:
http://www.new-kynoch.apt-sites.com/375%20flanged.htm
http://www.new-kynoch.apt-sites.com/cartridges%20named/375%20Flanged.jpg

The .375 Flanged Magnum Nitro Express was introduced by Holland & Holland in 1912 as a rimmed version of the world famous .375 Belted Magnum for use in single shot and double rifles. It boasts similar ballistics to its belted counterpart but to slightly lower velocities.


The 375 NE 2 1/2: http://www.new-kynoch.apt-sites.com/375%202%BD.htm
http://www.new-kynoch.apt-sites.com/cartridges%20named/375%202-5in.jpg

This .375 Flanged Nitro Express was introduced in 1899 and should not be confused with the Flanged Magnum of the same caliber which has a larger case. The cartridge was used in both single shot and double rifles and BSA made a bolt action rifle for this round as well.

I'm just reading an old thread from 2003
http://shootersforum.com/showthread.htm?t=5813&page=2
Article #26 from David White.
What an eye opener!!

Would the 375 Flanged work? How 'bout the 375 Nitro Express 2 1/2", or even the 9.3x74R necked to 375?

The 375 Flanged can be seen at:
http://www.new-kynoch.apt-sites.com/375%20flanged.htm
http://www.new-kynoch.apt-sites.com/cartridges%20named/375%20Flanged.jpg


The 375 NE 2 1/2: http://www.new-kynoch.apt-sites.com/375%202%BD.htm
http://www.new-kynoch.apt-sites.com/cartridges%20named/375%202-5in.jpg

Thank you.
I was thinking about the 2 1/2 and the H&H (2.85")is not going to fit, I tried a 9.3X74 and it didn't fit (2.9").
The 303 is about 2.25 as is the .348. Since I read the contribution I mentioned before, I'm more and more convinced to go with an Ackley Improved design.

mcgowen barrel.com scroll through barrels and read about the .338R . Basicly a rimmed 06 Rws case (7X65R case) with a Gibbs design. The .375 version should easily equal the 376 Steyer.

338

mcgowen barrel.com scroll through barrels and read about the .338R . Basicly a rimmed 06 Rws case (7X65R case) with a Gibbs design. The .375 version should easily equal the 376 Steyer.

338

Thanks 338.
I looked at that too.
One of the main problems in MY Martini is the size of the head. The .303 Brit. has a head of .540. I need the same size or greater. So far I have not found a resource for Martini extractors. If I had a spare or two, I could play around with it. The other Martini I have is/was a 14 1/2 Gauge Greener Martini converted by me to 12 Gauge. Short of making brand new extractors, well I'm very careful with the ones I have..:rolleyes:
I even thought of using the .303 case in an Ackley I. version. Even an "Ellwood Epps" biographer who made the .303 Improved Up in Orillia, Ontario had so far no data about a 375X303 Improved. I like the straight Case and now more so after reading David Whites article about "Backthrust in straight cases"
You can find it here:
http://shootersforum.com/showthread.htm?t=5813&page=2
Article #26 from David White.

Then there is the availability of reamers and dies. Right now, there is a set of reamers "on sale" for a 375X348 AI. I could use an old worn out die and ream it. (I know, anneal it first)
I'm still torn about the selection. I feel like a kid in a candy store and see all the selections, but am only allowed one.:confused:

Wolf

The .375 X 348 Payne express is an awesome cartridge. SInce I know less than nothing about the martini
action I would be concerned with what pressures the action was built for? The AI version or the Gibbs version has always been good for me with break open pistols. With the squared shoulders of a squared case I never have to push the shoulders back after the initual sizing after fire forming. Barrel diameter (OD) will also determine if the 348 case will work for you. A lot of metal must be removed to house that case.
I have a friend turning the belt off a belted mag case (.532) to make a beltless 375X338 Where is that reamer you refer to and how much is it. Of Course after you decide you do not want it.



338

Martini actions are strong, although I can't give any firm numbers. The real problem if you're rechambering them is selecting a cartridge that will fit over the hump at the rear of the action and slide into the chamber. Short fat cartridges make it, long thin one's don't. The action was made in two sizes at least, IIRC.

http://en.wikipedia.org/wiki/Martini-Henry

Scroll down to the action cut-away picture. The cartridge must be short enough to go over pin C without jamming in the chamber.

Bye
Jack

Thanks Jack!
I know, that I have to limit the CASE to 2.5" or less!1 Any case above 2.5 does NOT fit. So, I like to stay with a case that is less than 2.5". That doesn't mean COL; It can be greater!

"The 375 Win is a straight wall case, I'm looking for a shoulder; somethng like the 375 JDJ. BUT, I'm also looking at the Rimm diameter and rimm to body relation.
I surmise, that a bigger Rimm diameter produces less backpressure on the action, since you spread the backpressure over a bigger area and a straighter case clings better to a dry chamber."


Isn't the force on the bolt greater when you increase head size. Isn't that one of the reasons that contenders are limited to low pressure rounds in the bigger cases but just fine in the small high intensity cases. The pressure of the expanding gas is spread equally around the interior of the case. The area of the rear of the case would be what acts on the bolt. If you assumed the case did not do anything (oversimplification) wouldnt the equations below be accurate? Not trying to cause trouble just seeing if I am on the right track.

Pressure = force / area

.531 case head
60,000psi = F / (.531/2)squared * pi
F = 13260 lbs force

.473 case head
60,000 = F / (.473/2)squared * pi
F = 10560 lbs force

Close. The number you need is the maximum inside case diameter. That's the area the pressure has to work on. The ratio between inside case diameter and rim diameter can vary.

Bye
Jack

Test. Testing beta browser.

Bye
Jack

TXJM
I have the image in my mind...
High heels and Elephant feet you put the same weight on either and the high heels sink into the ground (small diameter) and the Elephant is not (greater diameter).
AM I on the wrong track??:confused:
Isn't it F= 60000/area ?:confused:

Wolf

Yes, Force = Pressure /Area. Area = (Diameter / 2)squared * pi (3.14159..)

Bye
Jack

Force = Pressure /Area. Area = (Diameter / 2)squared * pi (3.14159..)

341459.4116 for the .473 head
270939.5012 for the .531 head

Less pressure for the .303. Or am I off my rocker??

You are "on" your rocker, but using the wrong numbers.

As jack points out, it isn't the diameter of the case rim that counts, it's the diameter of the inside of the case, across the flash hole. That's the part of the case on which the interior case pressure acts, and is then transferred to the breechface.

Those numbers will be smaller, but proportional. So the concept that a smaller case transmits less force is valid. It's just the calculation that was in error. Clear?

Something is wrong with your math, as your numbers are at least 10X too high.

.473 / 2 = .2365"
Squared: .2365 X .2365 = .05593225
.05593225 X 3.141592654 = .1757 square inch (dropping insignificant digits)
.1757 sq. in. X 60,000 psi = 10542 lb force.

All old .303 reloaders have some expired brass around. Try .390" for the inside diameter of a .303 British case. Figure a .025" case wall on a .30-06 so .423" inside diameter.

Bye
Jack

Thanks guys for trying to enlighten me!!

Let me try to explain my reasoning:

Take a pencil and push it with 1000lb force, you penetrate a human body!
Take the same force of 1000lb and push it at the same human body with a frying pan, you do not penetrate.
On a frozen lake, if you stand on the surface, you fall through, but if you lay down, you don't.
High heels penetrate sand, put a 4 inch plate under it and it won't!

Am I wrong?

But then again, 60,000lb is still 60,000lb it is just spread out over a greater area.

Wolf

Those examples are correct, but misapplied. A better analogy is with hydraulics, where you get twice the force with a two-inch piston compared to a one-inch piston. (Square inch, not diameter.)

PSI still means Per Square Inch. (Pressure was originally written xxxx pounds PSI. Over the years, the "pounds" was dropped.) So if you change the number of square inches, you change the total force applied. A larger surface receives a larger force.

I think I have the final choice for my Martini Enfield project.
I'll stay with a .303 cartridge and use an Ackley Improved setup opened up to .375.
I don't have a cartridge drawing for a .303 Epps or Ackley Improved, I have one for a 30-40 Krag Ackley improved. The two cartridges are virtually the same in the base dimension.
Here is the Krag Ackley Improved:

All I have to do is expand to .375 :D

How 'bout the russian round, higher pressure and volume.


(lee)
7.62 x 54r 3.59 cc 50,000 psi
303 3.28 cc 46,000 psi
30-40 3.49 cc
356 win 2.91 cc

and make it an ackley too.

How 'bout the russian round, higher pressure and volume.


(lee)
7.62 x 54r 3.59 cc 50,000 psi
303 3.28 cc 46,000 psi
30-40 3.49 cc
356 win 2.91 cc

and make it an ackley too.
Thanks colville.
Yes, I thought about that cartridge too. If I would go for pure volume, I would go for the 348 or 45/70, but, it is still for a MARTINI action and like to stay in the same pressure range. If you look at the improved 30-40 cartridge, I want the same in the 303, i.e. shoulder pushed forward, 40 degree shoulder, caseweb to shoulder diameter difference about 0.010 max.

northwolf....
Any progress on this project???

I send an Email to Pacific Tool and Gauge, waiting for answers.
Have a better pic for the 30-40 Ackley improved.
I just told them to neck it up to .375 and leave the case as straight as it is. I think (and hope) that the straight case will reduce back thrust, as long as the chamber is free of oil!!
I might just get the 30-40 improved and use it on the Martini .303. To use it on a .375 barrel, I would use a .375 pilot bushing and a .375 neck and throat reamer.
I'll keep you informed.

Has anyone ever tried to do it the way I intend to do it?? I THINK it should work. In my old life;) I was (I am) a German trained tool and die maker!(Maschinenschlosser!!, Machine Tool Fitter??)

Thank you guys for all the help and suggestions. It made me look at some things differently. I'll give results and pics when I finished the project.
Again, Thank You!

Regards
Wolf

just picked up on yhis thread but...
the 7x57 rimmed would also work and can be ackley and 9.3 x57 data would be nice data wise
pressures are easily ran from 35,000 up to 50,000.

jesus now i have to get a single shot and a reamer and a barell

fivedog

jesus now i have to get a single shot and a reamer and a barel

fivedog

Yea, that is the problem with us!! Someone starts thinking out loud, or on paper and your own gears start turning in your head...:D

BUT, it's sooooo much fun, isn't it?

.376 Steyr reamer and dies+.45/90 brass,big enough?

WC