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Thread: 147gr GDHP - huge swings in velocity

  1. #1
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    147gr GDHP - huge swings in velocity

    I have an APC9 Pro that I was trying to zero at 75y. This provides the flattest trajectory from 0-100y.

    I was shooting over a Chrono because I also wanted to make sure they were staying subsonic.

    147gr Speer Lawman was fantastic. With 47 shots the SD was 9, Average 1056, and ES was 45fps. Rounds were right where I wanted them.

    147gr GDHP was not so nice. The first string of 15 GDHP average velocity was 1004, ES was 165fps, and SD was 24.

    The second string of 15 GDHP was 1070fps average, 57 ES and 14 SD.

    Sorry for all the numbers, but something was really funky with that first string of GDHP. All the rounds below 1020fps ish shot about 6-9 low at 75y. I would shoot, look at the velocity, and if it was around or below 1000 I would already know the shot went low before I even looked in the scope.

    Kind of a bummer because the Lawmens in this gun shot amazingly well. Almost no POI shift with or without the can either. But if Im shooting a 9mm I want HP ammo.

    Anyone ever had similar experiences with GDHP?

  2. #2
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    I will take my LabRadar and some Gold Dots and HSTs next time I take my APC9 Pro out and post back (as long as I remember).
    ETC (SW/AW), USN (1998-2008)
    CVN-65, USS Enterprise

  3. #3
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    Holy hell, that is a lousy endorsement.

    Have you pulled down a few and weighed charge Euro?
    Conjecture sucks, but variance in powder weight would be my first thought with that large of an ES.

    I run a lot of 124 GDs and have experienced ESs of 30-40 FWIW.
    A true "Gun Guy" (or gal) should have familiarity and a modicum of proficiency with most all firearms platforms, as well as the major Food Groups.

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    Im not sure if 0.2gr is enough to swing FPS that much but it was interesting with such a small sample size that the older lot had good consistency and the newer lot did not.

    Unfortunately I did not take note of lot #s when I was at the range.
    Last edited by Eurodriver; 03-15-20 at 15:51.

  5. #5
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    Differences in powder batch/lot seems the logical culprit.
    I would imagine Speer, with their ammo LE sales, would have an interest in the large velocity swings.
    I would identify ammo lot(s) at fault and contact them.

    They may want it returned and traded out.
    A true "Gun Guy" (or gal) should have familiarity and a modicum of proficiency with most all firearms platforms, as well as the major Food Groups.

  6. #6
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    High Extreme Spread and Standard Deviation numbers can be caused by faster gunpowders in a barrel longer than one found on a service pistol. Without knowing what gunpowder was actually used to load each cartridge, you won't have much luck finding an answer.

    Someone who works in the firearm ammunition industry told me that different lots of the same gunpowder perform differently. He said think of the difference in lot numbers as the difference in octane.

    I reload quite a bit of 9mm and .38 Special that gets fired in both handguns with 2" - 6" barrels and fired in carbines with 16" barrels. I am unable to use gunpowders with faster burn rates that work well in shorter barrels in the carbines and see good results.

    The numbers on the box flaps look like lot numbers. What are the product numbers on the outside of the ammunition boxes?
    Train 2 Win

  7. #7
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    Quote Originally Posted by T2C View Post
    High Extreme Spread and Standard Deviation numbers can be caused by faster gunpowders in a barrel longer than one found on a service pistol. Without knowing what gunpowder was actually used to load each cartridge, you won't have much luck finding an answer.

    Someone who works in the firearm ammunition industry told me that different lots of the same gunpowder perform differently. He said think of the difference in lot numbers as the difference in octane.

    I reload quite a bit of 9mm and .38 Special that gets fired in both handguns with 2" - 6" barrels and fired in carbines with 16" barrels. I am unable to use gunpowders with faster burn rates that work well in shorter barrels in the carbines and see good results.

    The numbers on the box flaps look like lot numbers. What are the product numbers on the outside of the ammunition boxes?
    53619

    Its only a 6.88 barrel which is 1.5 longer than a G34.

  8. #8
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    The Speer website did not list # 53619. The information I found on # 53619 from vendors is that Muzzle Velocity is 985 fps.

    Speer lists two offerings in 9mm 147g Gold Dot ammunition and # 23619GD has a published muzzle velocity of 985 fps. My best guess is the difference between # 53619 and #23619 is packaging and the number of rounds in the box. The Lawman is listed as # 53826 and has a published velocity of 985 fps, which should be the same velocity as your Gold Dots. There is a reasonable likelihood that the Lawman and Gold Dot HP ammunition are loaded with different gunpowders.

    I'll have to shoot some 147 Gold Dot HP through my CZ Scorpion to determine if I experience the same issue. I'll make it a point to shoot at 75 yards.
    Last edited by T2C; 03-17-20 at 22:40.
    Train 2 Win

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