BC 's effect on POI

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by winmagman, Jan 30, 2004.

  1. winmagman

    winmagman Well-Known Member

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    BC \'s effect on POI

    By mid Feb. I hope to have a new 6.5x284 in my hands. So I've been researching bullets, I think I've narrowed it down to four.

    SMK 140 gr., BC of .535 (high end of range)
    SMK 142 gr., BC of .595 (high end of range)
    Lapua Scenar 139 gr., BC of .574
    Barnes XLC or X 140 gr., BC of .522

    What I'm wondering is, what would the difference in POI be at 1000 yds. Assuming they were all launched from the same gun at around 3000 fps? Is a BC difference of .073 between the 142 MK and the Barnes XLC really going to gain me that much?
    Thanks for any input.
    Chris
     
  2. Varmint Hunter

    Varmint Hunter Well-Known Member

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    Re: BC \'s effect on POI

    In a word, YES. That's because the Barnes X bullet is gonna miss the target. LOL [​IMG]
     
  3. daveosok

    daveosok Guest

    Re: BC \'s effect on POI

    Did you give Berger's a thought 140 grain BC of .627?
     
  4. Michael Eichele

    Michael Eichele Well-Known Member

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    Re: BC \'s effect on POI

    The differance between .522 and .595 is about 20" of differance at 1k. Use the most accurate. Also BC's are not always what they say they are. I use some loads that the stated BC is higher than I am getting, other bullets are giving me more than the manufactures say I should. In a nut shell (and I agree w/VH on the barnes)use whatever your rifle likes. This is way more important than even 50" of differance.
     
  5. Dave King

    Dave King Well-Known Member

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    Re: BC \'s effect on POI

    Varmint Hunter

    ROTFLMAO... LOL... That's good.. I've also had "some" trouble with Barnes bullets in the past. The 168's in my 308 seem acceptable and they're a nice "Snurf" color.

    WinMagMan

    Select bullets based on accuracy as the first priority (the scope is adjustable to compensate for trajectory differences).

    When two different bullets are sufficiently accurate (and adequate for the task) select the one with the higher BC. Why throw away any advantage??? The difference between a BC of .522 and .595 at 3000fps and 1000 yards is 8 inches (10% difference) less wind deflection (theoretical) and 20 inches (7% difference)less drop (scope can compensate to no real issue).

    Good luck.
     
  6. winmagman

    winmagman Well-Known Member

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    Re: BC \'s effect on POI

    Varmit H, Yea, I hear they are a little tough to get to shoot well, but the were the highest BC true hunting bullet I could find. Thought I might give them a try.

    daveosok, I missed them but I'll definitly give them a look.

    meichele, Thanks , that's the number I was looking for. I thought I'd try the Barnes if the difference wasn't to great, I can live with 2 MOA. Now if I can just get the darn things to shoot well.
    Chris
     
  7. Michael Eichele

    Michael Eichele Well-Known Member

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    Re: BC \'s effect on POI

    winmagman,

    I always give barnes a try, I just have found only a few loads and usually only 1 load per rifle that will shoot em well.

    I had a load for my old VSSF 308 that shot the XBT 165 at 2900 FPS. That was with out the coating. Oh and it was about a .5 MOA load. My weatherby didnt shoot any of them well and my current 788 and 700 308's each have ONE load they shoot well with the barnes. I get out of my 700 the 150 XBT/XLC 2900 and .6 MOA accuracy. Thats not that good but makes for a heck of a moose or elk load! They have great terminal performance, just ask the 1500# moose I killed at 100 paces. Oooops! he's dead! [​IMG] For the terminal performance, they are worth a shot or 2. No pun intended. The only problem is there are so many differant kinds and they are SO expensive it can get expensive trying to find the one that works for you. I have shot groups at 770 yards that were quite impressive with the 180 XBT.

    [ 01-30-2004: Message edited by: meichele ]
     
  8. Brent

    Brent Well-Known Member

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    Re: BC \'s effect on POI

    Winmag,
    If that Barnes BC isn't inflated like most all of theirs are, by a long ways, (you are being forewarned here [​IMG]) accuracy will still probably be a problem with their BT bullets. The FB bullets seem to do OK, but getting the boattails to shoot can very often be a real B&^ch!!

    I would guess the XBT 140 to have a BC of about .450 if you're lucky! [​IMG] The A-Max, SMK and Lapua seem to be real close, sometimes a bit higher in the real world too... Barnes is not that way.
     
  9. Varmint Hunter

    Varmint Hunter Well-Known Member

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    Re: BC \'s effect on POI

    It may be me but I have also found that Barnes is a little optimistic about the velocities that are published in their manual.
    Inflated B/C's
    Inflated velocity
    Inflated ego [​IMG]

    They do, however, penetrate like crazy. I have never recoverd a single X bullet from a whitetail. Probably should stop shooting those little critters with my 7STW and those big copper bullets. [​IMG]

    VH

    [ 01-31-2004: Message edited by: Varmint Hunter ]
     
  10. winmagman

    winmagman Well-Known Member

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    Re: BC \'s effect on POI

    Thanks for all the great input. I think I'll still try a box of them, I just won't get my hopes up.
    Chris
     
  11. Michael Eichele

    Michael Eichele Well-Known Member

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    Re: BC \'s effect on POI

    Part of the reason the BC is inflated is that they are solid copper. They have a much differant specific gravity factor. It also takes a tighter than normal twist to get good stabilty out of em too becasue of this. If they were the length they are and jacketed lead, they would be the advertised BC and they would use a twist formula most of us use.

    They do smoke coming out of the barrel though. Have had 2900 FPS out of a 26" 12 twist 308.