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Double Rifles, Single Shots & Combinations >> Double Rifles
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mickey
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Reged: 05/01/03
Posts: 4647
Loc: Pend Oreille Valley, Idaho
Re: .375 Magnum vs Flanged in a double [Re: DUGABOY1]
      #5293 - 30/11/03 09:32 AM

Mac

Have you done this? I know where a very nice Heym two barrel set in 458WM and 375 H&H is at a very reasonable price. I had thought about the 450 3.25 or #2 but didn't consider it because of the Mag in 375. Isn't the body of the cartridge a bit different also?

--------------------
Lovu Zdar
Mick

A Man of Pleasure, Enterprise, Wit and Spirit Rare Books, Big Game Hunting, English Rifles, Fishing, Explosives, Chauvinism, Insensitivity, Public Drunkenness and Sloth, Champion of Lost and Unpopular Causes.

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DUGABOY1
.400 member


Reged: 02/02/03
Posts: 1340
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Re: .375 Magnum vs Flanged in a double [Re: mickey]
      #5295 - 30/11/03 10:31 AM

Yes Mick, they are different cases, and what you end up with is acentually a wildcat, that is formed by fireing a slightly shortened, factory Flanged case in the H&H chamber that has had the belt area is removed,bushed, and re-cut. Sort of like a 375 Flanged improved! Still you have a flanged cartridge instead of a belted rimless one, and ballistics are about the same. Here are the numbers, in inches!


375 Flanged/ 375 H&H Mag

case length 2.94 ............ 2.850

head dia .511 ............ .513

Rim dia .572 ............ .532

neck dia .404 ............ .405

neck length .444 ............ .300

shoulder Lgth .096 ............ .197

body angle .794 ............ .705

loaded length 3.08 ............ 3.60

belt dia N/A ............ .532

rim thick .05 ............ .o49

shoulder angle 13.47 .......... 7.95

Shoulder dia .450 .......... .460

case capacity 97.21 .......... 96.37 grs water

The 450 NE 3.25" or the 450#2 either will completely clean out the 458 Win Mag chamber, so it is a no brainer, but sometimes needs re-regulateing! Most times they don't, because they push their bullets at about the same speed.



--------------------
..........Mac >>>===(x)===>
DUGABOY1, and MacD37 founding member of DRSS www.doublerifleshooterssociety.com
"If I die today, I have had a life well spent, for I've been to see the Elephant, and smelled the smoke of Africa!"

Edited by DUGABOY1 (30/11/03 10:35 AM)

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DoubleD
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Reged: 23/11/03
Posts: 2392
Loc: Retired in Oklahoma
Re: .375 Magnum vs Flanged in a double [Re: DUGABOY1]
      #5297 - 30/11/03 11:36 AM

The measurements I found for the Flanged are are virtually the same as posted.

I do find some differences in the HH, but I'm not sure the are significant. The HH has a 15 degree shoulder for one thing.

The comparison of measurement of the head diameter is not relevant from belted to flanged as they are measured at two different locations. The belted is measured at .220 from the datum line and the flange is measured .060 from the datum line. Now I suppose If I did the math and projected the angle so they were in the same spot the difference would still be insignificant.

An alternative not mentioned was to simply bush the chamber to remove the belt but leave the H&H rim. Then turn the belts off H&H cases.

You would have a rifle marked .375 H&H and cases to match that are flanged and not belted also marked .375H&H.

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

Edited by DoubleD (30/11/03 11:43 AM)

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mickey
.416 member


Reged: 05/01/03
Posts: 4647
Loc: Pend Oreille Valley, Idaho
Re: .375 Magnum vs Flanged in a double [Re: DoubleD]
      #5298 - 30/11/03 01:19 PM

Nonononono, The problem isn't with the belt but with the rim. The case should head spaces on the rim not the neck or the belt.

--------------------
Lovu Zdar
Mick

A Man of Pleasure, Enterprise, Wit and Spirit Rare Books, Big Game Hunting, English Rifles, Fishing, Explosives, Chauvinism, Insensitivity, Public Drunkenness and Sloth, Champion of Lost and Unpopular Causes.

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4seventy
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Reged: 07/05/03
Posts: 2210
Loc: Queensland Australia
Re: .375 Magnum vs Flanged in a double [Re: mickey]
      #5300 - 30/11/03 03:24 PM

Mick,
Not sure what model Heym you were looking at but there is another thing to consider regarding rechambering these particular doubles to a flanged cartridge.

Some Heym doubles have the barrel spacing at the chambers so close that there is little room to accommodate a larger case diameter and definately NO room to accommodate the flange diameter.
A friend once owned a model 88 sidelock in 375 H&H belted mag and the chambers were so close together that they only just cleared the Greener type barrel extension.
The barrels were so close together that looking at them from the top it was hard to believe that they were chambered for 375.
If the gun you're talking about is the same action as that one my mate had then it may be too narrow to rechamber to flanged.
Worth checking out.

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mickey
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Reged: 05/01/03
Posts: 4647
Loc: Pend Oreille Valley, Idaho
Re: .375 Magnum vs Flanged in a double [Re: 4seventy]
      #5301 - 30/11/03 04:02 PM

When I get a chance I will check. The 4503.25 should be alright and the 375 barrels should be wider to accomodate the larger caliber in the 458. Might not work and that is why it is not a good idea to use rimless cartridges.

--------------------
Lovu Zdar
Mick

A Man of Pleasure, Enterprise, Wit and Spirit Rare Books, Big Game Hunting, English Rifles, Fishing, Explosives, Chauvinism, Insensitivity, Public Drunkenness and Sloth, Champion of Lost and Unpopular Causes.

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4seventy
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Reged: 07/05/03
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Loc: Queensland Australia
Re: .375 Magnum vs Flanged in a double [Re: mickey]
      #5302 - 30/11/03 04:27 PM

Mick, Have a look at this and you'll see what I mean.

www.mcdonaldsgunshop.com/archives/heym1.htm

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DoubleD
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Reged: 23/11/03
Posts: 2392
Loc: Retired in Oklahoma
Re: .375 Magnum vs Flanged in a double [Re: 4seventy]
      #5308 - 01/12/03 03:20 AM

If the issue was that the barrels were so close together that H&H couldn't be reworked to take the true flanged case then sleeving the H&H chamber to remove the H&H belt but leave the H&H rim would be the perfect solution. When the bushing was rebored it would have to be set to force the headspace to the H&H rim and not the shoulder.

Keep in mind on the cases you are turning off the belt and not the rim.

And again you would have properly marked barrels with properly marked cases for those countries that check that. I don't think they would notice that the belts were turned off the cases.

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

Edited by DoubleD (01/12/03 03:21 AM)

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mickey
.416 member


Reged: 05/01/03
Posts: 4647
Loc: Pend Oreille Valley, Idaho
Re: .375 Magnum vs Flanged in a double [Re: DoubleD]
      #5309 - 01/12/03 04:46 AM

Double D

One of the biggest problems with rimless cases, along with pressure, is the possibility of the little ear breaking, the tiny spring that pushes out the ear breaking or the whole little extractor getting dirty and failing to extract the case.

By removing the belt this problem is not addressed. If one was going to stick to a rimless case then having a belt would not be a hinderance one way or the other.

--------------------
Lovu Zdar
Mick

A Man of Pleasure, Enterprise, Wit and Spirit Rare Books, Big Game Hunting, English Rifles, Fishing, Explosives, Chauvinism, Insensitivity, Public Drunkenness and Sloth, Champion of Lost and Unpopular Causes.

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DoubleD
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Reged: 23/11/03
Posts: 2392
Loc: Retired in Oklahoma
Re: .375 Magnum vs Flanged in a double [Re: mickey]
      #5318 - 01/12/03 03:27 PM

Oh, I see what your getting at, the springloaded extractor needed for rimless and belted cases. Of course you are right...for belted and rimless cases.

Once you turn the belt off the H&H case you don't need the spring loaded extractor. A fixed extractor will work just fine. (Never worked on a Hyem so I don't know if it has a fixed extractor, it must because I see the .375 Fl MAG NE listed as one of the calibers it comes in.)

Keep in mind the H&H cases aren't in the truest sense rimless cases, they are rimmed cases with a belt. Once you turn the belt off they are back to being rimmed cases. The H&H rim is .523 in diameter, the head is right around .510

As far as pressure goes, removing the belt is not going affect anything. You will have a case constructed like any of the modern rimless cartridges. No different than say a 404 Jeff or .416 Rigby, except this one will have a rim and extractor groove. The head is going to be fully supported by chamber wall.






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

Edited by DoubleD (01/12/03 03:53 PM)

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