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Alliant Powder PSI Inconsistencies?

Discussion in 'Shooting Related Threads' started by WNCRob, Mar 12, 2011.

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  1. WNCRob

    WNCRob Member

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    I recently plugged in the following specs into the Alliant reloading program: Green Dot, 12 gauge Rem Hulls, 1&1/8th oz load, Rem 209's and Figure 8. The PSI values are obviously inconsistent and, to me, raise the question of the validity of any of them. I sent them an e-mail, but they seldom, if ever reply to matters such as these. I guess PSI accuracy isn't important to this powder manufacturer just as long as it isn't dramatically understated so as to be dangerous? Seems quite sloppy to me. Certainly not very professional. Love their powders, though.

    WNCRob
     
  2. grntitan

    grntitan Well-Known Member

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    How are you comparing the psi? Do you have a method of measuring it?

    Also define inconsistent.
     
  3. rennerize

    rennerize Active Member

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    WNCRob, it might be the 1/18th of an ounce that is causing the problem. LOL
    Don
     
  4. WNCRob

    WNCRob Member

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    Thanks for pointing out my error. There are 4 loads listed. The progressions are erratic...increase charge, PSI declines. Increase slightly and the PSI peaks dramatically. Maybe I shouldn't be so critical, but when dealing with explosives, I think they should deal with and correct obvious inconsistencies. In the past they have been very slow to make corrections; hence, my post.

    WNCRob
     
  5. grntitan

    grntitan Well-Known Member

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    Ahh yes. Now i get what your saying. That was brought up here once before. I thought i remember someone saying Alliant fixed that. Of course you know as you change wads pressure values usually change as well. I'm not saying this is the case though. I just misundertsood what you were asking or stating. I thought you were testing your loads and the psi was all over the place.

    I use the very load you stated with exception of the primer as i use Winchester with 19gr Green Dot. Good smooth shooting load.
     
  6. tanda1

    tanda1 Active Member

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    See it often on Alliant's site. In the below screenshot from today the 1145 fps load is obviously wrong...or is it? And, if so, how many others are wrong? And which ones? And how do we know? Completely agree w/ WNCRob...if they are going to put out data they should make certain it is correct.


    tanda1_2009_300730.jpg
     
  7. grntitan

    grntitan Well-Known Member

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    The second load is a misprint and should be 8,700psi.
     
  8. R.Kipling

    R.Kipling Well-Known Member

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    I have no idea if the published pressures are correct. However, I can tell you that there is a well observed adage in engineering - everyone expects nature to be linear, there is very little in this life that actually occurs in strict linear adherence.

    Gaussian curves (bell curves) can account for many things thought to be inconsistent. Just my SWAG for the day.

    Kip
     
  9. Jawhawker

    Jawhawker TS Member

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    When viewing a chart such as above it is obvious that second pressure reading should be 8700psi. I don't believe that Alliant or anyone working for them has any intention of placing our safety at risk.

    Errors happen in life and one has to accept. As for above pressure reading, atleast the mistake is not endangering anyone. Unlike many things we accept!
     
  10. Unknown1

    Unknown1 Well-Known Member

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    That's the wrong chart!

    The OP is asking for data containing Figure 8 wads, not WAA12

    Still, the velocity and pressure values are way mixed up... The way they're spaced I'd wonder if they belonged in the same chart:<center>
    [​IMG]
    </center>

    MK
     
  11. Quack Shot

    Quack Shot Active Member

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    A couple of things come to mind here. Number one is human error. It's very possible that the person(s) copying the data made an error. The other thing is that if the tests were done at different times and by different people, then the test results may be valid for when the testing was done WITH the exact components tested. Change the lot of powder, primers, wads, or atmospheric conditions, and you could have unexpected/different results. I had a discussion one time with a person that did pressure and velocity testing. Many times, the exact same results could not be reproduced two times in a row. They tend to publish what the results of the tests actually were, rather than what you would expect them to be. If they don't jive exactly to what you would expect, it illustrates a very good reason to treat the data as suspect and load conservatively. If the "experts" can't duplicate the loads exactly every time, how would a reloader expect to do so? I would advise you to call or write the powder manufacturer and make them aware of the discrepancies and get their take on it. If something needs to be retested and/or corrected, they would be the ones that would do so.
     
  12. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    Very good information Carl!! Ben @ Alliant will probably tell you the same things too. Different days, different numbers and they post what it reads.

    Hap
     
  13. WNCRob

    WNCRob Member

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    Yep, I wrote the company first. Typically, their response is very slow, if at all. Another person has advised me that the equipment is quite accurate at the higher pressures, and much less acurate at the middle pressures...guess that makes sense, and as long as we keep our loads under the max levels published, I suspect that is what the manufacturer expects us to do. Wish they would be more forthcoming, though. Guess the lawyers have a significant say in what they can publish. All-in-all, in this case, I have no faith at all in anything but the max pressure posted by the company.

    Thanks for everyones input on this matter.

    WNCRob
     
  14. Quack Shot

    Quack Shot Active Member

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    WNCRob

    I think the word would be "consistency" rather than accuracy. Many powders and loads do not become consistent until the pressure starts to climb a bit. Usually a phone call will get you a live body on the phone. More often than not, that person will have some insight into your question.

    There is a reason I have a good number of data sources at my disposal. I can look up a similar load in another manual for a reality check.

    As far as pressure limits, with all of the variables and suspect data, I do not load the highest pressure loads listed. I generally do not load over 10,000 PSI, with 9,000 to 9,500 my desired range. The pressure is high enough for some order of consistency and has enough headroom for a host of variables.

    I don't really worry about the one or two shells at 13,500 PSI. I worry more about the 50,000+ shells that follow at that same pressure or above.

    Hap

    I was once told that the only thing that a testing facility had control over was whatever components they manufacturered and how many samples they would test. They take a certain amount of variability for granted and do not expect to get the same exact results every time they test. If they are meticulous, they may get very close, but do they really test the same loads over and over? Look at how many loads are still listed in Lups and Cups. How old do you think that data is? Even pressure and velocity testing is a crapshoot. It can tell you what your loads did on a particular day on the equipment it was tested on, with the exact components and lots that you used and assembled on your equipment.
     
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