Magnum vs Standard Primers

Discussion in 'Reloading' started by Steven_CO, Mar 3, 2008.

  1. Steven_CO

    Steven_CO Member

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    Folks,

    I tried to search for the answer to my question, but could not find the data and/or can't remember where I read it, so I thought I would throw it out here.

    At what point do most decide to go with magnum primers vs standard primers in rifles?

    I usually follow the recommendations of the manuals, but in some combinations, it's not that obvious.

    As a rule, I have always assumed that over 70 gns and slower burning powders, like RL22, (I guess I could say when using a powder with a burning rate factor of less than 0.40) it's time to go bump it up to magnum primers.

    Does anyone else have a better source than my simplified rule of thumb?
     
  2. devildoc

    devildoc Well-Known Member

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    Well it's not a cut and dry thing. I'm sure you may absolutely need a mag primer in some of the monster cases like the RUMs and cartridges based on the .378wby and .408CT, But in my experience the cartridges based on the .375H&H case will take either mag or standard LR primers. Some load combos like mags some like standards.
     

  3. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    My rule of thumb is not all that clear cut either but her goes.

    When to use magnum primers:

    -When the case capacity is over 85 grains of stick powder
    -When the rifle will be used in temps below zero and especially below zero
    -When using more then 70 grains of ball powder(except Ramshot powders)

    Other possible times to try a magnum primer:

    -When velocity spreads are high and can not be decreased by bullet seating depth adjustment

    Other then that I generally use standard rifle primers.

    Kirby Allen(50)
     
  4. MagnumManiac

    MagnumManiac Well-Known Member

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    Steven CO,
    I use magnum primers in ALL ball powder loads, regardless of case size.I don't specifically look at case size as the pre-determinate either.If it is a case like the 25-06 Rem, I look at it's expansion ratio to determine whether or not to use a magnum primer or not.In this instance I use magnum primers for ALL powder types.The reason is because you need slow powders with this cartridge for it to perform correctly.
    In my other 06 based cases I use standard primers because the expansion ratio is lower,therefore more efficient.
    In magnum cases of any size I use magnum primers regardless, because when you are using very slow powders,under ignition is always high on the possibilities of something going awry.
    You can check this with a chronograph very easily.
    If you get big differences in velocity with a standard primer, then it's a good bet the powder in some cases is under igniting.
    Hope this helps.
    MagnumManiac
    gun)
     
  5. overbore

    overbore Well-Known Member

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    magnum primers

    May produce up to about 27% greater pressure than mild LR primers!!. I was taught, long years ago, "use magnums with 4831 and slower powders" but I agree that low temperatures and 4350 may require them. If we link the slow powder types to magnums, we then automatically cover the large capacity cases but I strongly disagree with their use on ball powders. Overbore
     
  6. MagnumManiac

    MagnumManiac Well-Known Member

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    Overbore,
    I don't understand why you 'strongly disagree' with using magnum primers with ball powders.
    My understanding of their make-up is that to change their burning rate,they are either made flatter,which increases the surface area,so they burn slower,or they are made smaller,which reduces their surface area,so they burn faster.
    The other factor they use to alter burning rates is the amount of deterrent coating they add to get the correct amount of burn rate.
    This significantly makes these powders harder to ignite than 'normal' stick or flake powders.
    Every ballistician I have spoken to says that a magnum primer with these powders is to be used,regardless of case size.
    If I am incorrect in these facts please show me some evidence to the contrary.
    MagnumManiac
    gun)
     
  7. overbore

    overbore Well-Known Member

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    Primers

    for military applications of ball powder are / were not magnums. I am referring to Nam area and the Mouse Gun. Overbore
     
  8. acloco

    acloco Well-Known Member

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    Depends on many factors - heat, temperature, humidity, powder, case style, etc, etc.

    Of note, I use ONLY CCI 450 magnum primers in my 17 Rem, 204 Ruger, 223, & 223 AI. Why? Primer cups are thicker and they deliver the best, most predictable and accurate performance. I use H4895 and Benchmark powders in the above calibers.

    Have ran several tests over my chronograph, some non magnum primers ignite powders just as well as magnum primers will.

    In the 300 win mag, using H4831, time will tell. Fed 210's work rather well, but so do the CCI 250's and the 215M's.