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Double Rifles, Single Shots & Combinations >> Single Shots & Combination Guns
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DoubleD
.400 member


Reged: 23/11/03
Posts: 2437
Loc: Retired in Oklahoma
375 MAG FL NE on MH
      #7754 - 29/01/04 05:14 PM

Still have to run electical power to the lathe. I have sitting here a .375 take off barrel , 375 MAG FL NE reamer, brass dies and a Martini Henry MK IV Action.

Does ony one know right off the top of their head if the 375 MAG FL NE will turn the corner to load in the MH action?

--------------------
DD, Ret.

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Levallois
.300 member


Reged: 27/11/03
Posts: 137
Loc: Arizona, USA
Re: 375 MAG FL NE on MH [Re: DoubleD]
      #7866 - 31/01/04 02:24 AM

DD,

Let me know how this works for you and whether you would consider making one for someone else and what it might cost. I've been thinking about the Martini action and the possibility of buying or making a very good SS sporting rifle out of one.

John

--------------------
It ain't like it used to be, but it'll do.

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DoubleD
.400 member


Reged: 23/11/03
Posts: 2437
Loc: Retired in Oklahoma
Re: 375 MAG FL NE on MH [Re: Levallois]
      #16442 - 06/07/04 07:44 AM

Took some time yesterday to do a little research.



I have the following items

1, A Westley Richards Martini Enfield style action that I picked up in South Africa a couple of years ago.

2. A .375 H&H barrel that was taken off a 98 Mauser.

3. 20 Rounds of .375 Magnum Flanged NE brass.

4. A .375 Magnum Flanged NE reamer.

It only seems logical to put them all together. But will they fit?

I made a barrel stub out of a chunk of old barrel.



Tried a dummy cartridge.



And it fit!

Now all I have to do is fit the barrel up and sights and make a forestock.fore


--------------------
DD, Ret.

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470Rigby
.333 member


Reged: 23/02/04
Posts: 328
Loc: Melbourne, Australia
Re: 375 MAG FL NE on MH [Re: DoubleD]
      #16443 - 06/07/04 08:52 AM

In reply to:

Now all I have to do is fit the barrel up and sights and make a forestock.fore



...but will the Martini-Henry action handle the pressure???

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DoubleD
.400 member


Reged: 23/11/03
Posts: 2437
Loc: Retired in Oklahoma
Re: 375 MAG FL NE on MH [Re: 470Rigby]
      #16444 - 06/07/04 09:15 AM

Of course it will! Don't sell the Martini design short, its a lot stronger action than most give it credit for. The Greener Martini actions were chambered in this cartridge.

The problem in this case is that this action is a commercial version of the military action, which is shorter and narrower than the Greener.




--------------------
DD, Ret.

Edited by DoubleD (06/07/04 09:35 AM)

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KWK
.275 member


Reged: 28/02/04
Posts: 61
Loc: Illinois
Re: 375 MAG FL NE on MH [Re: 470Rigby]
      #16552 - 10/07/04 04:09 PM

I'm not too familiar with the strength of the various Martini actions, but the pressure with the .375 Fl. Mag. is much lower than most people think.

The CIP rates it at the same pressure as the .30-40 and thus below the .303 Brit. Using CIP tables and assuming the "piston area" can be taken from the O.D. of the case, the .375 gives only about 10% more thrust than the .303.

The Flanged version is a slightly longer cartridge leaving more powder room, and it was spec'd at a lower fps despite being spec'd with the longer barrels often found with doubles and singles. These add up to much lower pressure. The Flanged is rated at 41,000 as indicated by CIP's crushers, and the Belted is at 54,000. (CIP crusher ratings typ. run about 1000 above SAAMI CUP.)

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470Rigby
.333 member


Reged: 23/02/04
Posts: 328
Loc: Melbourne, Australia
Re: 375 MAG FL NE on MH [Re: KWK]
      #16566 - 11/07/04 10:42 AM

KWK

These old Martini actions were originally designed for the 577/450 Black Powder cartridge, and were later adopted for Nitro cartridges when the 215 grain Mk V1 .303 was in vogue. This developed about 17 tpsi, so giving the Gunmakers of the day their due, I guess they deemed the action satisfacory for that pressure AND cartdridge head size.

Original ballistics for the .375 Flanged Magnum developed slightly more pressure at 18 tpsi, but the base area is substantially bigger than the .303 (.456" for the .303 and .511" for the .375).

Actually, in calculating "Bolt Thrust" it is the internal sectional area at the base that factors in, and to do a proper comparision, you would have to section some cases and measure that, but by my estimation, the difference between the thrust acting back on the Breech Block would be in the order of 30% higher with the .375 Flanged Magnum; that is if it was loaded to original ballistics!

The .375 Flanged Magnum, being essentially a handloading proposition, there will always be those that will be tempted to drop in a heavier pill....a few extra grains of powder...and...?

Just sounding a note of caution.....

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KWK
.275 member


Reged: 28/02/04
Posts: 61
Loc: Illinois
Re: 375 MAG FL NE on MH [Re: 470Rigby]
      #16576 - 11/07/04 03:50 PM

Yes, earlier ratings for the old cartridges might not be the same as with the current CIP ratings. I suspect the CIP rating for the .303 is based on the later military pressures. I remember trying to estimate the pressures via the QuickLoad simulator and finding the .303 was at lower pressure than the .375 Flanged. Also, I see I used a base diameter too small for the Flanged. Based on just the CIP numbers, I should have reported 13% more thrust.

You mentioned that one should use the I.D. of the case instead of the O.D. While this should give a better number than O.D., I use O.D. to estimate thrust because it gives a more conservative number. For your calculations, based on tsi, you need to use O.D.

There's a good article in the April, 1967 American Rifleman by the technical liason for the old Kynoch. He clearly states that when reading pressures with base crushers (as was done with the tsi ratings you give), one must use the O.D. to compute the thrust. Indeed, this is how the tsi rating for case diameters other than that of the .303 was computed by them. Base crushers require the use of a well oiled case, and I believe the chamber pressure is being carried throughout the oil film, thus the need to use the O.D. Sadly, the fellow didn't state why one must use O.D., but I believe my guess is correct.

While not relevent to this discussion, he also noted that base crushers underestimate peak pressure more than the radial crushers (I would have guessed it to be the other way around), and of course both were found to be low when the piezo sensors were used. He also noted that dry chambers give thrusts about 3/4 that of oiled chambers.

Perhaps our friend should consider the fine old 400/350 instead. I believe I'm safe in saying it's thrust is no greater than the old .303 loadings.

------------------------------------------------------------------

Uh, kindly disregard my blather on O.D. and base crushers. That obviously deals only with making the pressure measurement in the lab. One's gun uses a more or less dry chamber, and with that, I.D. gives a closer estimate of the effective piston area. Thrust is also affected by the yield strength and thickness of the brass a bit above the web. Comparing the relative piston areas using O.D.s shouldn't be too far off, though.

Edited by KWK (12/07/04 05:37 PM)

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KWK
.275 member


Reged: 28/02/04
Posts: 61
Loc: Illinois
Re: 375 MAG FL NE on MH [Re: KWK]
      #16577 - 11/07/04 04:38 PM

Ooops, I really goofed.

I went to Kynamco's site and got their numbers for performance of the early British rounds. I cranked these through QuickLoad to get a rough estimate of pressure. In place of cordite, I used Reloder 15 since modern reloaders report it regulates well. I get the .375 Flanged running about 30% more pressure than the early .303, which was a very low speed round in comparison, only 2050 fps. The CIP pressure limits for the .303 must be based on later loadings.

Together with the bigger base diameter, one then gets about a 2/3 increase in breech thrust over the .303 -- ouch!

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NitroXAdministrator
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Reged: 25/12/02
Posts: 39877
Loc: Barossa Valley, South Australi...
Re: 375 MAG FL NE on MH [Re: KWK]
      #16579 - 11/07/04 07:04 PM

Martinis like that have been successfully made into .375 2 1/2 inch cases. Not sure of the pressure comparisons. There was a discussion somewhere on the NE.com forums where it was mentioned. Search under "Martini".





--------------------
John aka NitroX

...
Govt get out of our lives NOW!
"I love the smell of cordite in the morning."
"A Sharp spear needs no polish"

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DoubleD
.400 member


Reged: 23/11/03
Posts: 2437
Loc: Retired in Oklahoma
Re: 375 MAG FL NE on MH [Re: NitroX]
      #16581 - 11/07/04 09:46 PM

If the .375 H&H is indeed a 50,000+ cup round, this rifle will not be built in this caliber. The action is deemed safe for rounds in the 45000 cup range.

I have no concern about me shooting safe .375 Flanged Mag loads in the rifle. I just don't have control of what the next guy will do.

I will build a 450 Musket # 2 or .375 2 1/4 flanged on the action instead.



--------------------
DD, Ret.

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KWK
.275 member


Reged: 28/02/04
Posts: 61
Loc: Illinois
Re: 375 MAG FL NE on MH [Re: DoubleD]
      #16587 - 12/07/04 03:05 AM

Again, the Flanged is at a lower pressure than the belted. CIP's rating (above) seems low if Kynamco is correct in using 2425 fps for the 300 gn load; I'd thought it was 2350 or even 2300. Since you have the components on hand, you could use them and stamp the barrel ".375 DoubleD" or ".375 D&D" and add the fps rating, maybe 300 gn at 2150 fps, still a potent load.

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bpesteve
.300 member


Reged: 18/11/03
Posts: 106
Loc: Sunset side up
original pressures [Re: DoubleD]
      #17073 - 23/07/04 09:55 AM

Wright's book has a great set of appendices, one of which is a list of cartridges and pressures from the 1925 Nobel Industries catalog:

.303 Mk VI (215 gr)----17 tons
.303 Mk VII (174 gr)---18.5 tons
.375 Fl. Mag-----------18 tons
.375 Belted Mag--------20 tons

other catalog entries document the two loads of:

.375 2-1/2" Fl---------14 tons - 270 grain load
.375 2-1/2" Fl---------17 tons - 320 grain load (uncommon)

We all know there's no direct conversion to CUP or psi, but the above numbers are a good set of comparitive values.

Great project!

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DoubleD
.400 member


Reged: 23/11/03
Posts: 2437
Loc: Retired in Oklahoma
Re: original pressures of .375 Fl Mag NE [Re: bpesteve]
      #17145 - 25/07/04 06:39 AM

I can't let it go. I have been doing more research and I have come to the conclusion if I treat the .375 Flanged Magnum NE as a different cartridge from the .375 H&H belted Magnum and make sure my barrel is marked accordingly I am on safe grounds.

I am correcting the headspace on a 577/450 Sporter Martini right now. I have the barrel in the lathe waiting for the reamer to come from the rental place. As soon as I get that job done the .375 barrel goes in the lathe.

--------------------
DD, Ret.

Edited by DoubleD (25/07/04 09:38 AM)

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