Questions about 155gr. Sierra Match King Palma

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Duff, Jul 14, 2005.

  1. Duff

    Duff Well-Known Member

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    After trying some 168 MK's in my .308 (and not finding the accuracy I wanted) I tried some 155 Sierra Palma bullets and accuracy is definately better (1/2 moa). Is the advertised BC of .450 accurate? Why do Palma rules dictate that 155's be used? (rather then 168's or 175's?) Does anybody else here shoot these?
     
  2. James Jones

    James Jones Well-Known Member

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    Not to sure about the history of the 155 and why it has to be used but the BC is accurate they have a very high for weight BC. The shoot wel out of my guns but not as well as the 175 MK's
    You should try the Lapua Scenar's in 155gr their BC is .500+ and they are realy consistant
     

  3. Michael Eichele

    Michael Eichele Well-Known Member

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    One benefit of the 155 is that they can be fired at much higher velocities out of the 308 than say the 168's. They also seem to give a higher real world BC than the 168. This = less drop and less drift. While some 168 loads fired from a 308 might not even make it to 1K, the 155's most certanly will deliver themselves to 1K with ease and good accuracy to boot. It seems that the Palma bullets dont do much better than 7-8" at 1K, but that aint bad either. I have had good luck with all the 155's. The Palma, AMAX and Scenar. Have found the Palma to give as much as .460 BC depending on the barrel I am using, 474-485 for the AMAX and .500-.510 for the Scenar. All have shot perfect holes at 1k even in -5 to -20 degrees F. at sea level. Thats pretty impressive. The AMAX's have done as well as 3.5", the Scenars have done as well as 5 inches and the Palmas have done as well as 7.5" at 1K for me.
     
  4. Duff

    Duff Well-Known Member

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    thanks meichele, that is the info I was looking for. This is an informal target gun (I hope to have a good 600 yard paper puncher when I get done) it only has a 20" barrel on it so I was thinking the lighter bullet and faster velocity might be helpful for 600 yards. I'm sure eventually, I'll try the 175 MK's. thanks again-Duff
     
  5. milanuk

    milanuk Well-Known Member

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    I believe part of the reason for the weight restriction had to do w/ the old rules of using issued ammo provided by the host country... most of the NATO countries that used the .308 Win round use a bullet weight around 147-150gr or there abouts, or about 10g (a Lapua 155gr Scenar is marked as 10g on the box). Part of the HP fascination w/ super tight bores (.298x.3065) came from some of the issue ammo being rather undersized compared to commercial bullets, so in order to keep pressures and velocities up, shooters went to tighter bores. Somewhere along the line the 155gr SMK became somewhat of a standard, so the ultra-tight bores weren't strictly necessary but they held the minds of many for years and years. Now I think even the 155gr SMK 'standard' is no longer in force, as other bullets such as the 155gr Scenar is seeing a lot more interest, at least here stateside.

    Another part of it is that when you start stretching the distance on a .308... you start running the edge of the envelope, so to speak, as far as bullet weight, B.C. and velocity. Some of the heavier bullets might have gonga B.C.'s, but at some point, a moderate B.C. and enough speed trumps a higher B.C. and a slower speed. Case in point would be a 190gr SMK moving out at 2600fps, vs. a 155gr SMK @ 2950... the 190 blows less in the wind, but not much... less than one click on the sight, actually, and it tends to wear out the barrel faster. A 175gr SMK @ 2750fps runs right about the same wind as a 155gr SMK... but change that to the 155gr Scenar, and you pick up about a minute worth of wind advantage. Obviously you can ram-rod the crap out of a 190 or a 175 and change the equation some, but a price has to be paid somewhere, either in barrel wear or recoil or both

    The 155gr requirement came about by what would seem to be a rather capricious way, but ended up being little to no actual handicap in reality, at least not considering the cartridge restraint.

    YMMV,

    Monte
     
  6. BountyHunter

    BountyHunter Writers Guild

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    Just beware that Palma barrels are not run of the mill 30 cal barrels. Comparing them to standard 30 cal barrel is like apples and oranges.

    They are special tight bore barrels that are normally 30" long with 1-13 twist. They are made to shoot only one bullet, the 155. Extra 4-8" sure helps MV along with the tighter bore.

    Higher MV (2950 fps) helps them get to 1000. However, you are going to be hard pressed to get that MV out of a 22-26" normal 30 cal barrel.

    BH