7mm mag

Discussion in 'Reloading' started by Gills, Aug 19, 2018.

  1. Gills

    Gills Active Member

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    Am new to reloading have the basics down and am playing with 150 gr hornady elf-x bullets and federal 215 primers with hornady brass. Currently using 64 gr n160 getting a 1/2 group at 100 yds. But was wanting to see how much more velocity I could get. So I started adding .5 gr and test fired them at 65 gr a shell split just above the belt but had no pressure or heat signs up to this point. Should I have seen pressure signs other than this first?
     
  2. Barrelnut

    Barrelnut Well-Known Member

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    How many times had the shell that split been reloaded? Belted magnums require a couple of advanced loading techniques to make the shells last longer for reloading.
    Basically you need to fire the shell about 3 times and neck size only until the case gets resistance when closing the chamber, then bump the shoulder back 2 thousands. This allows the shell to index off of the shoulder instead of the belt as belted shells were originally designed to do. Tons of stuff written about this on the forum.

    You need a set of these so you can measure the shell size from the datum of the shoulder to the base of the shell.
    https://www.midwayusa.com/product/1...headspace-gauge-5-bushing-set-with-comparator
     
    Hand Skills, Dosh and cape cove like this.
  3. cape cove

    cape cove Well-Known Member

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    I believe this is more a case sizing problem than a pressure one. Size your cases as Barrelnut pointed out and you should be good.
     
  4. Gills

    Gills Active Member

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    Not sure how many times it’s been reloaded I have not kept track. I did originally start full length resizing but am neck sizing now.
     
  5. Gills

    Gills Active Member

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    I have a Ron’s neck sizer die. How do you adjust the neck bump. Just screw it a little farther. Probably a dumb question. Just the only adjustment I’ve noticed on it is the primer ejector pin
     
  6. Gills

    Gills Active Member

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    I’m sorry it’s a rcbs neck sizer die. Damn auto correct
     
  7. Barrelnut

    Barrelnut Well-Known Member

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    You need a full length sizer die to size the body of the shell and push the shoulder back. Or since you already have a neck die, you can get a "body" die that just sizes the body and then use the neck die to size the neck. Usually a two dir set contains a full length die that sizes the neck and body at the same time and a seater die to seat the bullet.
     
  8. Gills

    Gills Active Member

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    I also have a hornady full length die. So maybe I miss understood. Neck size, untill they are tight in chamber or as u said resistance closing the chamber, then use full length sizing due to bump back the shoulder
     
  9. Barrelnut

    Barrelnut Well-Known Member

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    Yes that's it! But you have to learn howto setup the Hornady Full length die so that it only bumps the should back ~2 thousands. You need the Hornady Headspace Gauge set mentioned above to effectively do that. You can also do it by setting up the FL die so that it is off the shell holder by a turn or so and keeping sizing the piece of brass and turning the die about 1/16 further down each time. After sizing the piece of brass try to fit it in the camber and turn the die down another 1/16 until the bolt just closes on the piece of brass with no resistance.
     
  10. Gills

    Gills Active Member

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    I ordered them already. So that will hopefully help. I believe I can adjust my full length die down so it does it’s job befor the die is completely Barrie’s in the die I guess I will have to just play with it.
     
  11. Gills

    Gills Active Member

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    Any body else using this powder and bullet weight in a rifle with a 24 inch barrel? How much powder weight and how much velocity are you getting out of it.
     
  12. MudRunner2005

    MudRunner2005 Well-Known Member

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    65 grains of a fast-burning powder like N160 is a pretty stout load, as it is...Even with a 150 grain bullet.

    Sounds like you hit a pressure spike... Did the split look like this?

    7mm STW case:head separation.JPG

    That's a picture of one of my 7mm STW brass that had a pressure spike, and it never showed any sign of pressure when shooting, so I cleaned them, and when I was drying them, I noticed several cases had this issue. I did some investigating and discovered that it had been a combination of crappy brass, work-hardened brass, and pressure spikes. Bought some new (better) brass, swapped to slower burning powders, and no more issues.
     
  13. Gills

    Gills Active Member

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    Yes similar but much shorter
     
  14. Gills

    Gills Active Member

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    What would a better powder be I have also tried 4831 and 4831 sc but couldn’t get them to group. Would 4350 be a good choice to try