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9mm Factory Velocity Variation

Discussion in 'Handloading and Reloading' started by Carphunter, May 13, 2008.

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  1. Carphunter

    Carphunter Member

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    This weekend, I got a chance to bang away with my new toy, used nickel Sig 226.

    For s & g's, I was shooting over my chrono with several different factory loadings.

    I noticed in my strings of ten shots per ammo type, I was seeing some real interesting variations in velocities.

    With Wolf 115 FMJ, UMC 115 FMJ, Fiocchi 115 HP, and Fiocchi 124 FMJ, I'd get some some shots that were within 50 fps of each other, but then I'd get rounds that would drop considerably.

    I don't have my notes in front of me... so I'll use B.S. numbers... but they do represent the variation I'd see. I might get 8 shots at 1500fps, but two at 800 or 900. Also might get a way hot load up at 2000.

    THe only ammo I shot that day I didn't see that kind of variation on was some old Remington green box 124 fmj.

    So... is that kind of variation in factory ammo common?

    FYI, the low-power shots were not first out of the barrel, or last. So I don't think I was seeing some variation of cooking the ammo.

    Or, could the Sig in some way have an issue that could cause this? (I don't know...light spring that allows ejection too soon).

    Or would you suspect chrony error? (I shot some three-shot strings of rifle rounds over the chrony that day...and saw no weird readings.
     
  2. rcmodel

    rcmodel Member in memoriam

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    Sounds to me like your crony screens were set up too close to the gun.

    The only way you could possibly get 8 shots at 1500fps and one at 2000fps out of a 9mm pistol is to chrony the muzzle blast!

    I just re-read your post, and now see those were BS numbers, but still, I would suspect muzzle blast if you are getting variation of BS 800 to BS 2000.

    rcmodel
     
  3. Carphunter

    Carphunter Member

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    just fyi, chrony was 10 feet in front of muzzle.

    I'll try to post the real numbers tonight when I get home.
     
  4. amlevin

    amlevin Member

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    I am of the belief that the variations are more due to the chrony than the ammo. Were you indoors or out? Was it sunny or cloudy?

    If you were indoors the chrony could have been influenced by fluorescent lighting which often causes high readings. If outdoors, uneven lighting could cause erratic readings.

    Lighting is the larges single cause of inaccurate readings on chronographs. This why most are installed in an enclosure (coffin) with separate lights in order to remove these variables when chronographing for competition.

    Factory ammo is not all that consistent and can vary widely from mfr to mfr but the kind of spread(s) you indicate most likely go back to the chronograph.
     
  5. Carphunter

    Carphunter Member

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    Outdoors, overcastish...not direct sun, but not dark either.

    chrony mounted on a heavy video tripod.

    Just thinking, I'll also be putting some rifle rounds over it tomorrow... I'll see if I see any inconsistencies then.
     
  6. amlevin

    amlevin Member

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    I find the most consistent readings are when I aim low in the "v" of the screen supports. The closer the bullet passes in relation to the photo cells, the better the reading. I caution, however, that your aim has to be real good. Use soda straws instead of the wire supports and try without the screens. That way anything but a low shot won't do any damage.
     
  7. Carphunter

    Carphunter Member

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    I'm inputing the data for the different ammo.

    Reading it, and seeing that there isn't any weird numbers in my rifle data, or in the Rem. Green box ammo... I'm wondering if there wasn't some majorly different thing happening with sun/cloud cover. I didn't get any shots, though, where the speed didn't register (which I've seen before).

    For everyone's info, readings from the different ammo:
    UMC 115 FMJ
    1076
    772
    1071
    1054
    791
    1574
    1059
    1064
    769

    Wolf 115 FMJ
    1122
    1811
    1713
    1133
    1766
    1101
    789
    1801
    1120
    796

    Fiocchi 124 FMJ
    1133
    1128
    821
    821
    1139
    830
    1854
    1787
    1846
    816

    Fiocchi 115 HP
    1260
    1223
    2017
    1246
    1247
    1957
    2109
    2038
    859
    1266

    Rem 115 FMJ Green Box
    1054
    1092
    1064
    1052
    1054
    1071
    1045
    1046
    1059
    1052
     
  8. rodregier

    rodregier Member

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    My vote in on a chrono issue somehow. I find it difficult to believe your 9mmx19 pistol would have extracted and ejected the fired case with a 115g @ 700 or 800 ft/sec. That's too anemic for proper function with normal springs. With that much variation the sound of firing would probably have varied a lot too.
     
  9. Steve C

    Steve C Member

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    I've found that factory ammo shoots to their listed ballistic data +/- a reasonable difference expected from using different firearms. In all those I've ran over my chrono factory ammunition has been consistent with relatively low SD values.

    I've chrono'd wolf ammo from my Glock 19 along with a small variety of othe factory loads.

    For Wolf the average velocity was 1,219 fps with a SD of 19.74 fps. Range was from a low of 1,191 fps to a high of 1,242 fps.

    Fiocchi 115gr JHP Italian manufactured ammo ran 1,288 fps average. SD was 13.92 fps with a range from 1,272 fps to 1,310 fps. Fairly hot ammo comparable to Corbon and other +P loads.

    Winchester Ranger SXT +P+ 127gr JHP's (police surplus) ran at 1,273 fps with a SD of only 8.53. Range was 1,261 to 1,285 fps. Very accurate ammo.

    Some Barnual Silver Bear 145gr bi-metal nickle plated cased ammo ran at 1,054 fps average with a SD of 8.54 and a range of 1,042 to 1,067 fps. Very accurate ammo also but alas, it wasn't reliable in extraction and would seize in the chamber occasionally making the case removal difficult.

    115gr FMJ S&B ammo was relatively tame at 1,142 fps average SD of 17.73 fps with a range of 1,114 to1,161 fps.

    If there are any flashes of light it will throw off the chrono. I once tried to take measurement when there was a far off lighting storm and even at a great distance the readings became erratic. Occationally I've seen erratic readings from light glinting of the windshields of cars dring by. Any fluorescent lighting really throws of the readings as the lights pulsate and flicker.
     
  10. Carphunter

    Carphunter Member

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    I can post numbers later... but in yesterday's shooting, moved the chrony to 15'.

    No errant readings.

    When I have time, I'll try again at 10' and see if the issue comes back.

    While setting up, realized sun was probably less over head than the first day.

    btw... the fiocchi 115 HP's are some fun buggers.
     
  11. RidgwayCO

    RidgwayCO Member

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    Save that Fiocchi brass too ("GFL" headstamp). I've been very happy with it in 9mm Luger and .38 Special.
     
  12. Carphunter

    Carphunter Member

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    New Numbers.
    Chrony at 15' in front of muzzle

    Don't have anymore UMC...so no numbers

    Wolf 115 FMJ
    1129
    1105
    1100
    1072
    1072
    1091
    1083
    1064
    1043

    Fiocchi 124 FMJ
    1124
    1118
    1123
    1128
    1128
    1117
    1123
    1128
    1115
    1112

    Fiocchi 115 HP (APHP, not the xtp stuff)
    1196
    1193
    1216
    1235
    1240
    1215
    1216
    1195
    1233
    1221
    1222
    1216
    1218
    1241

    Rem 124 FMJ Green Box
    1035
    1060
    1061
    1054
    1048
    1050
    1047
     
  13. rcmodel

    rcmodel Member in memoriam

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    That looks a lot more better!

    rcmodel
     
  14. Walkalong

    Walkalong Moderator

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    A lot "mo better" rcmodel, didn't your English teacher teach you anything? :D
     
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