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Comparing recipes from Hornady and Lyman books

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  • schick79

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    Waiting on getting all my equipment in, so I'm reading up in the two books I have. I was comparing 9mm recipes from both the Hornady and Lyman books, and I'm confused on what I'm seeing.

    The first picture below is from Lyman, and the second is from the Hornady book. I'm looking at the Power Pistol powder.

    The Lyman book shows 5.9 grains = 1257 fps and 6.5 grains = 1409 fps.

    For Hornady, 6.0 grains = only 1150 fps and 6.4 grains = 1200 fps.

    Why is there such a discrepancy between the two recipes' velocity when it's the exact same powder with nearly identical weights, and both recipes are using the 115 gain XTP bullet?

    Does the primer choice and/or case used make that much of a difference on velocity?
    Photo Oct 19, 9 32 17 PM.jpg
    Photo Oct 19, 9 32 45 PM.jpg
     

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    kendive

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    I use the powder manufacturer's load data. But that does look odd. ?

    Same here I just use the manufacturers load data from there website for the most part and come up with my own for subsonics with alot of testing and data collecting.
     

    SAWMAN

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    I suspect that the load data numbers are a direct result of the bbl lengths used in their test guns.
    I have seen people overpressure their guns by trying to obtain the figures from a 6" bbl in their snubby.
    This is especially true with rifles. Internal chamber pressure does not have very much to do with overall bbl length. The obtained velocity is directly influenced by how long the bullet stays in the bbl and is allowed to accelerate with the expanding gases/building pressure.
    A hot load is a hot load,no matter the bbl length.
    Let's all stay safe out there. --- SAWMAN
     
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    SAWMAN

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    Also - - -> Primers can make some difference if they are magnum or not,and some primers are just hotter/quicker or colder/slower between manufacturers.
    Cases can make a difference also. Much more so with rifle brass though. Given the outside diameter is all the same,some cases are thicker which makes the inside volume smaller which can influence the pressure levels and how fast it rises. I weigh most all of my rifle brass. Hardly any of my pistol brass. ---- SAWMAN
     

    schick79

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    Thanks, all. All of this is of course new to me. Didn't even realize the powder manufacturers had their own data outside the manuals. So much to learn... going to be taking it very slow, and probably asking lots more questions. Appreciate the GCGF community very much!
     

    schick79

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    Saw - I don't have the Lyman book handy but the Hornady book said their barrel used was a 4". If I remember correctly, the Lyman's data came from some sort of carbine. Will check and report back tonight.

    For primers, Hornady specified a Winchester WSP, and I think Hornady was CCI.

    I suspect that the load data numbers are a direct result of the bbl lengths used in their test guns.
    I have seen people overpressure their guns by trying to obtain the figures from a 6" bbl in their snubby.
    This is especially true with rifles. Internal chamber pressure does not have very much to do with overall bbl length. The obtained velocity is directly influenced by how long the bullet stays in the bbl and is allowed to accelerate with the expanding gases/building pressure.
    A hot load is a hot load,no matter the bbl length.
    Let's all stay safe out there. --- SAWMAN
     

    schick79

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    Well... 4" barrel for both books...
    Hornady's primer was Winchester WSP and Lyman's was CCI 500.
     

    Jester896

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    Sierra and Nosler info is very close to the Hornady info
     

    boatbum101

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    You have to look at the components used in that particular load . 9mm is a PITA IMHO . Not all bullets are equal some occupy more case space . Also COAL effects pressures & as stated above primers are different too . Any time you differ from published load data ie different vase , bullet , primer etc start low & work your way up .
     
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