EXTRAPOLATING FOR REDUCED LOADS?

Discussion in 'The Ammo & Reloading Forum' started by mgatc, Jan 9, 2011.

  1. mgatc

    mgatc New Member

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    Re-read the section in Lees' manual pertaining to the effects on pressure and velocity by reducing the charge in 1% increments. (Chapter 9 - A 1% reduction in charge equals a 2.5% reduction in pressure and a .9% reduction in velocity)

    I wanted to load .357mags with berrys 125gn and Unique powder but the velocity was too high.

    Berrys instructions say to load using the middle to lower end of the jacketed data and not to exceed 1200fps.

    Page 552 of the Lees manual shows 125 grain jacketed bullet with Unique powder at 8.7gn to start and 9.6 not to exceed.

    I tested the theory using the NEVER EXCEED load and then began reducing the load by 1% at a time until it matched the START LOAD. I did the same thing with the velocity using a .9% reduction as suggested and it was withing 7fps of the published velocity.

    I continued to extrapolate this formula until the velocity dropped below 1200fps at 7.1gn of powder. I even continued beyond this point to a velocity of 1044fps at 6.2gn of Unique. Lee suggests this can be done safely down to a third of the published load.

    Is my understanding correct? Can I safely use this formula to determine a reduced load below that which is published? What else should I be aware of?

    m
    Last edited: Jan 9, 2011
  2. carver

    carver Moderator

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    I'm not up to date on this, but why not try another powder? I personally use the loads posted in the manuals. If the powder I have on hand won't get me what I want, then I just buy a different powder that will. My reasoning is that if the reduced load is what I want, then I will probably be shooting quite a bit of ammo with this load.
  3. BillM

    BillM Active Member

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    Berry's plated bullets? Use lead bullet data. Berry's bullets are
    soft lead, with a VERY thin copper plating. You can push them a little
    faster than plain lead, but not much. Most jacketed data is way too
    fast.

    FWIW, watch your crimp. Overcrimping berry's bullets will cut the plating
    and accuracy will be suffer.

    Personally I prefer a good cast lead bullet, usually moly coated. Works fine
    for light loads and lots cheaper than Berry's.
  4. JLA

    JLA Well-Known Member

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    you have essentially put a mid range .38 special load in a .357 mag case, which it is safe to do...

    DISCLAIMER!!!-It is not safe to stuff .357 magnum loads in a .38 special case!!!
  5. mgatc

    mgatc New Member

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    I tossed all of my .38 cases when I began handloading to avoid the potential of loading a magnum round in a sub mag case.

    Does anyone on the forum use this method to create reduced loads?
  6. steve4102

    steve4102 Former Guest

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    Lee data is nothing more than a copy of others data. In the case of your 357Mag I believe it is Speer/Alliant data.

    Lyman 48 lists the following.
    357 Magnum
    125gr Hornady JHP
    1.590 OAL
    Unique, Start-7.0gr-990fps---Max-9.7gr-1358fps
  7. steve4102

    steve4102 Former Guest

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    I do not. I don't like to go below published Min except with H-4895 in rifle rounds.
  8. JLA

    JLA Well-Known Member

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    I personally would go the route carver mentioned and use a powder that yields lower velocities. Trailboss comes to mind. and itll do it with a full case of powder so you get good load density and a light recoiling load, whats not to love about that???
  9. noylj

    noylj Member

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    Yes. Best powders for reduced loads (because they have been so used for decades) are Unique and Bullseye. As you go to lower velocities, you should move to Bullseye.
    The only "problems" are going so low that you stick a bullet in the bore. Going down to about 700fps is no problem.
  10. mgatc

    mgatc New Member

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    As long as get the rounds below 1200fps I should be ok with the Berrys'.

    I'm showing 1202fps with 7.2 gn of Unique down to 1044fps with 6.2. I had planned to stay within these parameters.

    Trying to ensure that my calculations were in the ball park
  11. JLA

    JLA Well-Known Member

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    go smack between the 2. it should be cruisin along at about 1125, which is a decent plinkin load. itll still level steel plates and wont recoil your hands off...
  12. woolleyworm

    woolleyworm Active Member

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    I'm trying to take this from step one here; Is this a load that you have worked up before, or a new load? Are you're saying that you STARTED your load development from 9.6gn and worked backwards??

    A published MIN load is just that, if you go below that, then youre into a range which isn't published as safe " by that reference, be it Lee, Hornady, etc "

    I will read the Lee manual tonight to see the exact section that you're talking about as far as the 1/3 issue. "Lee suggests this can be done safely down to a third of the published load." There's a reason that they publish min loads; while I agree that there are "safeties and cushion" within the published data, I wouldn't go off of "suggestions", go by Exact and what is published unless you have a true NEED to experiement outside a lab/testing environment.
  13. mgatc

    mgatc New Member

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    WW,

    Not sure where to start.

    I have not ever used other than a published load.

    Published loads for the bullet/Powder combo that I want to use exceed the recommended velocity for the bullets. (Berry's 125gn copper plated).

    So yes, I am trying to create a load that will safely utilize the berry's bullets and Unique powder. To do this, I am applying the precepts in Chapter 9 (See first post) of Lee's reloading Manual.

    I have not, as of yet, actually loaded any shells using this theory. I posted my question here to see if anyone can confirm that this theory is valid and usable. If so, then, did I apply it correctly to arrive at a safe recipe.

    m
  14. noylj

    noylj Member

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    My manuals show a 'recommended starting load' but not a 'minimum safe load.' I think someone is reading more into the 'starting load' than actually exists.
    It is a load that should be safe in all guns in good shape and properly chambered for that cartridge to act as a start load. Not that a lighter load is NOT SAFE.
    Likewise, I sure hope the poster didn't actually start at the max load and work down.
  15. mgatc

    mgatc New Member

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    I have gone back and re-read all of these posts and realized that I my wording may have led to some confusion.

    When I posted that I had started at the "never to exceed" load and worked down, I was referring to the extrapolation formula - not actually loading rounds this way!
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