Quick Question: why is there a belt on Belted magnum

Discussion in 'Handloading and Reloading' started by Mark_Mark, Jan 26, 2022.

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  1. Mark_Mark

    Mark_Mark Member

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    Head Space?
     
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  2. LocoGringo

    LocoGringo Member

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    Yes, a belted magnum headspaces off of the belt rather than the shoulder.
     
  3. Mark_Mark

    Mark_Mark Member

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    that’s smart, like a rim. I was messing with my brass for 375 H&H and was think… must be head space. Then why would they headspace from the shoulder ??? the belt seams more consistent
     
  4. Grumpy_old_Fart

    Grumpy_old_Fart Member

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    Because the 375 h&h was designed for a double rifle, and extraction was critical. When the design of the rifle changed to a bolt,the belt wasn't needed, but the brass was common. Then the cartridge evolved.and that's why many magnums had belts.
     
  5. Mark_Mark

    Mark_Mark Member

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    Thanks! wonder why they never made a straight wall belted . you guys think Belted will be a thing of the pass?
     
  6. redcon1

    redcon1 Member

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    Because it was the easiest way to ensure reliability at the time when manufacturing tolerances were not what they are today. Headspacing off the shoulder is much much preferable and now that we can control our tolerances better, the belted magnums should just go away because they are more of a detriment than a benefit but the belted magnums retain a legion of loyal followers who will ensure that it persists long past its expiration date.
     
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  7. JT-AR-MG42

    JT-AR-MG42 Member

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    Headspace is correct.
    The belt was first used on Holland & Holland's 400/375 bolt action because the minimal shoulder required a different method
    of maintaining headspace. The American .400 Whelan did not have the belt and suffered (in popularity) for it.

    H&H also used the belt on their 300 and 375 H&H, again to control headspace on the tapered sloping cases.
    Those two cartridges found such great favor in the U.S. that both Winchester and Remington needlessly
    succumbed to the belted mania when they started designing the
    standard length magnums (with case shoulder angles that were fine for headspacing) in the 50s.

    Actually H&H used unbelted rimmed versions of both the 300 and 375 in their double rifles.
    After WWII, companies started playing with side by sides adapted to rimless cartridges.

    JT
     
  8. Grumpy_old_Fart

    Grumpy_old_Fart Member

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    I stand corrected.
     
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  9. Grumpy_old_Fart

    Grumpy_old_Fart Member

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    The 375 and 300 H&H arrived in America in the 1920s. Winchester started chambering rifles for the 300 after Ben Comfort took a win with it, Western Cartridge started making ammo. It was the first cartridge that Roy Weatherby wildcatted into the 270 Bee. Then all the manufacturers want a piece.
     
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  10. Walkalong

    Walkalong Moderator Staff Member

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    In theory.
     
  11. 243winxb

    243winxb Member

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    In a large chamber, head spacing off the shoulder may cause the area in front of the belt, to become unsupported. After a few loadings, resized rounds may not chamber. More so with neck sized only brass.

    https://www.larrywillis.com/ Die maybe needed?
     
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  12. jmorris

    jmorris Member

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    Yeah, they worked to keep the long gradual tapered cases from being seated too deep. Unnecessary on many rounds they are found on, just an “expected feature” on “magnum” rounds for a long time.

    With my 300 WM rifles, I headspace off the shoulder, despite them having a belt.
     
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  13. Rule3

    Rule3 Member

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    You have no "quick" questions!:)
     
  14. Legionnaire
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    Sort of like the apocryphal story of the woman who always cut both ends off her roast before roasting. When asked "Why?" by her daughter, she said "Because that's what my mother used to do." So daughter calls grandma to ask why she cut the ends off a roast. "Because a whole roast wouldn't fit in my small pan."

    Belts may have made sense early on, but there was no reason to put one on the 7mm Remington Magnum. So I prefer the .375 Ruger over the .375 H&H.
     
  15. Mark_Mark

    Mark_Mark Member

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    Before I knew about headspace (thanks Larry Potterfield) I thought it was for extra Magnum support
     
  16. Mark_Mark

    Mark_Mark Member

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    Why don’t you like the belt?

    I think it’s the prettiest case ever! very elegant
     
  17. Jim Watson

    Jim Watson Member

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    The intent of the belted cartridge was, as said, to hold headspace on a shallow or tapered shoulder Cordite cartridge and feed like a rimless in a bolt action.
    Why is the 7mm Remington Magnum belted? Because H&H, Weatherby, and Winchester magnums are belted and Everybody Knew that magnums are belted. Maybe also because they were already set up to produce that head diameter and belt.

    My question is, why are the 1960s generation SHORT Magnums at 2.5" case length? OK, 2.6 for .300 Win Mag.
    Winchester had been making .300 and .375 H&H for years, the Model 70 is long enough for the 2.85" rounds.
     
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  18. South Prairie Jim

    South Prairie Jim Member

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    We say headspace off the shoulder but actually we are spacing the opposite end.
     
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  19. Legionnaire
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    To each their own. I have a 7mm Rem Mag that I inherited from my FIL, but I prefer the look and functionality of the .280 Ackley Improved. When I see the belt, I think "superfluous" rather than "elegant."
     
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  20. Mark_Mark

    Mark_Mark Member

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    I have some 8mm Remington Magnum (4 boxes) made in the old Remington Bridge Port Plant in 1981-ish. That’s a beautiful round, one day I hope to find a rifle for it

    We use to play in that abandoned plant when we were kids!
     
  21. Slamfire

    Slamfire Member

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    If you look at old British literature from the period, there are all sorts of "proprietary" equipment and rifles from British Gun Makers. Just take a look at the number of types of locking mechanisms for British double rifles.

    Double Gun Bolting Systems Spindles, Bites and Underlugs

    Each maker creates a slightly different thing, be it cartridges, iron sights, etc, and touted as the end of history. Moderns should not get uppity: how many USB connectors are there?

    The belted magnum was one solution that for a double rifle that was carried over to bolt rifles. I consider the belted cartridge a poor choice for magazine feed as I have had rim lock in a 375 H&H Magnum. I loaded 235 grain bullets, which made the cartridge shorter than the magazine box by maybe 3/8". That rifle still recoiled heavily, which caused cartridges to slide in the magazine. And during rapid fire exercises, I had the top cartridge move behind of the bottom cartridge, and then the belt of the top cartridge caught on the rim of the lower, causing a jam. I had to recognize that I had a jam, fully open the bolt, and push down on the cartridge stack, then close the bolt, to clear the jam. Those are things I would not want to do in a panic situation. I want to concentrate on the threat, not the diagnosis of a mechanical failure.

    What I have found of interest, are comments from the inprint crowd that the original H&H cartridges produced less velocity, and hence, less pressure than the American standardized version. I wish I knew the original H&H pressures. But it makes sense that the original H&H cartridges were far lower pressure than what we buy over the counter today. H&H was using these things in double rifles, which are not mechanically rigid, and in WW1 era Mauser actions, where were built for a 43,000 psia 8mm cartridge


    Gun Digest 1975 has an excellent article, “A History of Proof Marks, Gun Proof in German” by Lee Kennett.

    “The problem of smokeless proof was posed in a dramatic way by the Model 1888 and its commercial derivatives. In this particular case a solution was sought in the decree of 23 July 1893. This provided that such rifles be proved with a government smokeless powder known as the “4,000 atmosphere powder”, proof pressure was 4,000 metric atmospheres or 58,000 psia. The 4000 atmosphere proof was standardized for the 1893 and continued after 1911.


    Rifle Magazine Issue 159 May 1995 Dear Editor pg 10

    http://www.riflemagazine.com/magazine/PDF/ri159partial.pdf


    Ludwig Olsen :

    Mauser 98 actions produced by Mauser and DWM were proofed with two loads that produced approximately 1000 atmosphere greater pressure than normal factory rounds. That procedure was in accordance with the 1891 German proof law. Proof pressure for the Mauser 98 in 7 X57 was 4,050 atmospheres (57, 591 psi). Pressure of the normal 7 X 57 factory load with 11.2 gram bullet was given in Mauser’s 1908 patent boot as 3,050 atmosphere, or 43, 371 pounds.

    While many Mausers in the 1908 Brazilian category will likely endure pressures considerably in excess of the 4,050 atmospheres proof loads, there might be some setback of the receiver locking shoulder with such high pressures


    When you take pressure and convert it into loads, these are the loads that Mauser built his action to 8 mm Mauser cartridge loading. As a comparison, the loads from a 300 Win Mag. :

    From Cartridges of the World

    8 mm case head diameter 0.470” Area 0.1735 square inches
    300 Win Mag case head diameter 0.515” Area 0.2083 square inches

    Bolt face loads

    8mm (Mauser design loads) 0.1735 in ² X 43, 371 lbs/ in ² = 7, 525 lbs

    300 Win Mag = 0.2083 in ² X 65,000 lbs/ in ² = 13, 539 lbs

    The 300 Win Mag provides an 80% increase in bolt thrust over standard military loads.


    I believe that once Winchester chambered their M70 in 375 H&H, an action made from 4140 steel, not the 1035 used in Mauser actions, that Winchester set the industry pressures at a much higher level than would be safe in military Mauser actions. But that was of no concern to Winchester, or anyone else for that matter, as the British were adhering to their Mausers and hiding their proprietary standards for the cartridges.
     
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  22. MEHavey

    MEHavey Member

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    In modern 375 H&H bolt actions -- if you want to save your
    brass from head separations -- size to the shoulder
    and forget the belt.
     
    Last edited: Jan 26, 2022
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  23. DM~

    DM~ Member

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    That's NOT accurate, the 375 double rifle cartridge, wasn't "belted", is was/is "rimmed".

    DM
     
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  24. jmorris

    jmorris Member

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    The other end is more difficult to “bump back” with my press.

    Ah perspective…:)
     
  25. Grumpy_old_Fart

    Grumpy_old_Fart Member

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