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Double Rifles, Single Shots & Combinations >> Double Rifles
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AussieMike
.300 member


Reged: 01/09/04
Posts: 236
Loc: Southern Tablelands, NSW, Aust...
Rim Thickness
      #27358 - 06/03/05 08:50 PM

I need to know the rim thickness of:

375 H&H Flanged Magnum;
375 H&H Belted Magnum (just the rim behind the extractor groove, and;
375 2 1/2" NE (and also its rim diameter - COTW says .523 which seems small).

Having maligned Bertram Brass, possibly unfairly, it has occured to me that my case life problem may be head space related.

Rifle Cogswell and Harrison box lock non ejector converted from 375 2 1/2 to 375 H&H Flanged. Bertram cases last 2-3 firings whereas I get 8+ reloads from 375 H&H Belted cases when I lathe turn the rim off. I load 75gn AR2213 (H4831) under a 250gn projectile for 2450fps so it should be running under the 375 2/12" 17 tpi.

Thanks for any help.

mike

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wombat
.300 member


Reged: 06/03/04
Posts: 163
Loc: Australia
Re: Rim Thickness [Re: AussieMike]
      #27359 - 06/03/05 09:45 PM

?cartridges of the world specs-worth a look??

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AussieMike
.300 member


Reged: 01/09/04
Posts: 236
Loc: Southern Tablelands, NSW, Aust...
Re: Rim Thickness [Re: wombat]
      #27360 - 06/03/05 09:58 PM

Only has rim thickness on a few British cartridges.

mike

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pwm
.300 member


Reged: 15/06/04
Posts: 216
Loc: Banana Republik of Germany
Re: Rim Thickness [Re: AussieMike]
      #27363 - 06/03/05 11:14 PM

375 flanged 1,52mm
375 h&h rim thickness 1,27mm, length from head to belt5,59mm
375 2,5" rim thickness 1,63, dia.13,41mm

this is max. in the CIP list

have only one time work with bertram, was 11,2x60R mauser,the brass was to hard. careful anealing is maybe allways the secret with problem brass.

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AussieMike
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Reged: 01/09/04
Posts: 236
Loc: Southern Tablelands, NSW, Aust...
Re: Rim Thickness [Re: pwm]
      #27399 - 07/03/05 08:09 AM

pwm,

Thanks - it doesn't seem that headspace is the problem as the 375 Belted cases should give more than the Flanged, but I'll try and measure the actual brass I've got.

How far down did you anneal the brass? Just the neck, or the whole case, or somewhere in between.

thanks,

mike

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475Guy
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Reged: 22/08/03
Posts: 1088
Loc: Kali, US
Re: Rim Thickness [Re: AussieMike]
      #27404 - 07/03/05 09:48 AM

You always anneal the neck only down to just where the shoulder starts. Otherwise, you'll get overly soft brass.

--------------------
Lo do they call to me,
They bid me take my place among
them in the Halls of Valhalla,
Where the brave may live forever.

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4seventy
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Reged: 07/05/03
Posts: 2210
Loc: Queensland Australia
Re: Rim Thickness [Re: AussieMike]
      #27409 - 07/03/05 11:13 AM

Mike,
Case life is reduced when case lengthening occurs.
This can happen even if the rim thickness and headspace at the rim is correct.
If you are pushing the shoulder back in the resizing die, and then the shoulder is moved foward when the cartridge is fired, then it gets pushed back again during sizing, and so on and so on, this will reduce the working life of the case and can cause head seperations.

Other issues which can lead to head seperations include FL dies which reduce the dimensions of the case wall diameter/s in relation to the chamber dimensions, and double rifle actions going off the face and as a result increasing the headspace.

Never never never anneal any part of the case other than the neck and maybe the shoulder if necessary.
Brass cases need to be of a certain hardness at the head to be able to contain the pressure.
Serious accidents due to soft brass have occured when the case head has been softened as a result of being heated and the case head has expanded and released hot gas under high pressure.

Edited by 4seventy (07/03/05 01:11 PM)

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AussieMike
.300 member


Reged: 01/09/04
Posts: 236
Loc: Southern Tablelands, NSW, Aust...
Re: Rim Thickness [Re: 4seventy]
      #27432 - 07/03/05 04:58 PM

4seventy,

I'm hoping that's the problem and that's one reason I'm going to try neck sizing only (the other reason is that I've got a separated case stuck in my FLS die).

I still fear it's not the only problem as belted cases last 8+ reloads (with the belt turned off, of course). BTW, in another post you raised the issue of wheher the residual rim was enough to allow adequate headspacing - in my rifle it is, in fact the case doesn't slip past the extractor on loading, tho it does on extraction about 1/2 the time.

thanks,

mike

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unspellable
.300 member


Reged: 06/03/04
Posts: 187
Loc: Iowa
Re: Rim Thickness [Re: AussieMike]
      #27526 - 09/03/05 06:03 AM

Cartridges of the World is not always helpful and occasionally wrong. Especially where British sporting rifle cartridges are concerned.

On the other hand I have a book devoted entirely to British sporting rifle cartridges, their dimensions and load varients. I'll try to look these three cartridges tonight and report back tomorrow.

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unspellable
.300 member


Reged: 06/03/04
Posts: 187
Loc: Iowa
Re: Rim Thickness [Re: unspellable]
      #27570 - 10/03/05 03:18 AM


Rim measurements from drawings

375 H&H Belted per Kynoch drawing:

Thickness: 0.050 inch
Diameter: 0.532 inch

375 H&H Flanged per Kynoch drawing:

Thickness: 0.060 inch
Diameter: 0.572 inch

375 Flanged Magnum per ICI Metals Ltd drawing

Thickness: 0.060 inch maximum
Diameter: 0.572 inch maximum


Rim measurements from samples
(British manufactured cartridges)

375 Belted Rimless Magnum:

Thickness: 0.042 to 0.055 inch
Diameter: 0.527 to 0.532 inch

375 Flanged Magnum:

Thickness: 0.052 to 0.060 inch
Diameter: 0.557 to 0.572 inch

375 2-1/2 Inch Flanged Nitro Express:

Thickness: 0.059 to 0.065 inch
Diameter: 0.520 to 0.528

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unspellable
.300 member


Reged: 06/03/04
Posts: 187
Loc: Iowa
Are the 375 belted & 375 Flanged the same? [Re: unspellable]
      #27571 - 10/03/05 03:25 AM

For years I had thought the 375 Magnum Flanged was simply a rimmed version of the 375 Magnum Belted. While looking up rim thicknesses I found this is not so. The 375 Flanged differs in many measurements from the 375 Belted.

Most significant, the case length, length to shoulder, and OAL are all greater than the 375 Belted. Enough so that if you shaved the rim off it could not be expected to chamber in the 375 Belted chamber.

This as opposed to the 400-360 Rigby Rimless which will chamber and fire very nicely in a 400-360 Rigby Flanged chamber.

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4seventy
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Reged: 07/05/03
Posts: 2210
Loc: Queensland Australia
Re: Are the 375 belted & 375 Flanged the same? [Re: unspellable]
      #27577 - 10/03/05 09:43 AM

In reply to:

This as opposed to the 400-360 Rigby Rimless which will chamber and fire very nicely in a 400-360 Rigby Flanged chamber.



Tell us more about these 400-360 Rigby rimless and flanged cartridges.
I am not familiar with either.

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unspellable
.300 member


Reged: 06/03/04
Posts: 187
Loc: Iowa
Re: Are the 375 belted & 375 Flanged the same? [Re: 4seventy]
      #27578 - 10/03/05 10:19 AM

There are about five different 400-360 cartridges which differ from each other by slight variations in the bullet diameter, weight, and powder charge. They all used the same case with slight variations in neck diameter to accomodate the variations in bullet diameter.

The 400-360 2-3/4 Rigby Flanged had 41 grains of Cordite, and a 0.360 inch bullet of 314 grains weight.

The rimless version was manufactured by the simple expedient of putting the flanged case in a lathe and machining off the rim and cutting an extractor groove. It carried the exact same load as the flanged version. This was the only rimless cartridge among the various 400-360's.

It was for a Rigby magazine rifle that must have been custom ordered with no more than a handfull made. But the cartridge was listed in one of Rigby's catalogs. It's obvious that turning cases in a lathe is not a mass production technique. Examples of this cartridge are quite rare these days.

Edited by unspellable (10/03/05 10:21 AM)

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4seventy
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Reged: 07/05/03
Posts: 2210
Loc: Queensland Australia
Re: Are the 375 belted & 375 Flanged the same? [Re: unspellable]
      #27586 - 10/03/05 12:30 PM

In reply to:

The 400-360 2-3/4 Rigby Flanged had 41 grains of Cordite, and a 0.360 inch bullet of 314 grains weight.




What date was this cartridge designed?

I thought the 41 cordite 314gn bullet 400/360 was credited to Westley Richards not Rigby.

A .360" bullet?

Rigby already had their 400-350 NE which used 43gn cordite with a 310gn bullet of .357" dia and was used in bolt action rifles as well as doubles but both used the same FLANGED cartridge.

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unspellable
.300 member


Reged: 06/03/04
Posts: 187
Loc: Iowa
Re: Are the 375 belted & 375 Flanged the same? [Re: 4seventy]
      #27607 - 11/03/05 12:51 AM

My God! You are right! I must have had my brain dis-engaged. All the above was about Westley Richards, Rigby had nothing to do with it! We are talking about the Westley Richards 400-360 flanged and rimnless. As for dates of introduction, I'll have to look and see what I have. I think the first of the five 400-360 cartridges appeared circa 1903.

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