Belted Magnum Head Spacing

Discussion in 'Reloading' started by LongWalker, Jul 31, 2018.

  1. LongWalker

    LongWalker Well-Known Member

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    I have searched myself into a stupor so I thought I'd just ask the exact question regarding belted magnums and head spacing. Once a new case has been fired, if it's not FL resized (just neck sized) the once fired case will head space off the shoulder not the belt?

    I ask as with all my other cartridges I just neck size and bump the shoulder every 4 or 5 firings and I'd really like to be consistent with the process.
     
  2. J E Custom

    J E Custom Well-Known Member

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    This is correct.
    Also the normal way to load for accuracy in a belted case. If you want the advantage of easy chambering (A must on dangerous game) then full size belted cases. The down side of this is less case life.

    Some dont like belted cases, but once you size them just enough to chamber, they are no longer efectivly a belted case, Because they head space on the shoulder.

    J E CUSTOM
     
  3. LongWalker

    LongWalker Well-Known Member

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    Excellent. That's very helpful.

    To bump the shoulder I use a Redding body die which also sizes the case body. Any issues with the area above the belt bulging since I'm thinking the body die won't hit the belt?
     
  4. Laelkhunter

    Laelkhunter Well-Known Member

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    If you have expansion (bulging) in front of the belt, look into the Larry Willis Collet die. Works wonders. larrywillis.com
     
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  5. Azrael

    Azrael Well-Known Member

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    I've had issues with cases being tight above the belt; but for the most part they were man-made problems. The most common cause is using cases that were fired in a much larger chamber first. Depending on the vagaries of chambers and dies you might not be able to size to suit. A small base die will usually take care of those. As a side note, a .300 Win SB die with the stem removed will put the squeeze on all the shorter belted magnums of lesser caliber as well. One of these days I'll cut one in half to work on the larger and longer as well, but the Willis tool works on all of them.

    The other instance is tight chambered barrels, reduced base reamers and head-spacing so short that the bolt wouldn't even come close to closing on a go-gauge. What a waste of time that turned out top be. However, while suffering through those mistakes for nothing, the SB die and Willis tool got a work-out. These days if I use either its for some sort of salvage operation.
     
  6. lancetkenyon

    lancetkenyon Well-Known Member

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    I FL size my 7RM and bump the shoulder .002" just like any other case. I have 8-9 firings on some of them. Not ridiculously hot loads, but a great hunting load pushing a 180 Hybrid @ 2996fps. So I would consider it "warm", but no signs of pressure.
     
  7. MudRunner2005

    MudRunner2005 Well-Known Member

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    It will actually be headspacing off of both the shoulder and the belt. Keep doing exactly the same process with the belted mags, as you do with your others, and you'll be fine.
     
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  8. J E Custom

    J E Custom Well-Known Member

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    If it is new brass it will form to your chamber, If it has been fired in another chamber it is best to full size it the first time.

    All brass/cases should be fired in the chamber that they will be used in. with quality brass that is consistant, I will set head space with the go gauge and check the head space using the cases to be used to make sure that they will fit the chamber. Todays brass/cases are all over the place. Some have belt dimensions that are minimum specafication and others are maximum SAMMI dimensions.

    The minimum dimension is .220, the maximum is .227 so it is best to check the brand of cases before you set the final head space. If you intend to use as shouldered cases, You can head space to maximum and fire form using reduced loads. My preference is to set the head space at .002 more than the case and once fire formed use the shoulder, and that way if I want to full length size i will only have .002 thousandths instead of almost .007 and risk case head seperation.

    J E CUSTOM
     
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  9. dig

    dig Well-Known Member

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    Same advice, bump .002 and be done with it. I load multiple Weatherby cartridges, 8 even 10 times fired full length sized with a polished expander. Have used the on dangerous game on two continents. The belt was more of a marketing gimmick when it first came to popularity. Everyone had to have a “belted magnum”. Lots of incorrect therories out there about spacing on the belt.
     
  10. Azrael

    Azrael Well-Known Member

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    Normally I'll use the Redding Competition Shell-holders and bump .002".
     
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  11. g0rd0

    g0rd0 Well-Known Member

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    I tried all of the tricks and dies, some worked some did not. Almost 10 years ago a friend gave me a lee collet die set and use it till I find stiffness in closeing the bolt then I full length size and carry on. Usually I get 8 loadings before I notice stiffness.
     
  12. Bull383

    Bull383 New Member

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  13. Bull383

    Bull383 New Member

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    I have been trying to reload for my 338-378 Weatherby and I keep getting the slight bulge just above the belt causing tight bolt closing. I have been using the redding competition shell holders to bump the shoulders back. I have smoked up the brass to confirm where the tightness is and it is indeed above the belt. The Willis die will not work on the 338-378 does anyone have a suggestion? I can only get 4 reloads and then I start to get case head separations. I have reloaded for a 257 WBY and 340 for years and never had a problem.
     
  14. dig

    dig Well-Known Member

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    The Willis die does not work on these cases unfortunately, to big. Keep playing with the dies, I use a Forester press so no shell holder and have not had any issues. Just checking but are you bumping the shoulder too much. I found in my redding press that if I am setting the shoulder back too much it caused the bulge, pushed the whole case into that strong belt and that was my issue. Also in my 300 wby switched to Redding dies, which helped.