Velocity testing of premium 270 win factory ammunition (mostly mono-metal)

Discussion in 'Up To .375' started by matt85, May 19, 2019.

  1. matt85

    matt85 AH ENABLER AH Legend

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    ive been bored lately with no vacation time to go hunting (nor the budget) so I decided to test a bunch of factory ammunition in my Merkel Helix rifle chambered in 270 Win. the barrel length is 22 inches and the average temperature during the testing was 75F. I greatly prefer mono-metal ammunition so most of this ammunition uses some variant of copper or gilding metal bullet. the Power-point was tested because its cheap and I had a box.

    Mono-metal ammunition:
    - Winchester Deer Season XP Copper Impact 130gr: average velocity 2929 fps (claimed velocity 3000 fps)
    - Barnes VOR-TX LR 129gr: average velocity 2988 fps (claimed velocity 3140 fps)
    - Barnes VOR-TX 130gr: average velocity 2917 fps (claimed velocity 3060 fps)
    - Hornady Superformance GMX 130gr: average velocity 3125 fps (claimed velocity 3190 fps)
    - Federal Trophy Copper 130gr: average velocity 2984 fps (claimed velocity 3060 fps)
    - Browning BXS 130gr: average velocity 2944 fps (claimed velocity 3100 fps)

    other ammunition tested:
    - Winchester Power-point 130gr: average velocity 2957 fps (claimed velocity 3060 fps)
    - Federal Nosler Accubond 140gr: average velocity 2847 fps (claimed velocity 2950 fps)
    - Federal Edge TLR 136gr: average velocity 2904 fps (claimed velocity 3000 fps)
    - Federal Trophy Bonded Tip 140gr: average velocity 2845 fps (claimed velocity 2950 fps)


    -matt
     
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  2. JimP

    JimP AH Elite

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    That's about right, I always figure that with factory ammo it will be between 100-200fps slower than what they claim. However the ammo manufactures are shooting through test barrels and not actual rifles.

    Other than that, I hope that you didn't go out and purchase all those boxes of ammo for your testing. I know that when I have done a few things like that I beg and borrow a few rounds of each from some friends that shoot factory ammo. Or use their factory ammo to try and come up with a duplicate load when they want me to load some rounds for them.
     

  3. matt85

    matt85 AH ENABLER AH Legend

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    these velocity numbers are actually just a bi-product of me looking for a good factory load to use in my 270 Win. while almost all of this stuff was on sale, to be honest im so used to shooting large bore stuff that even the most expensive 270 Win is incredibly inexpensive by comparison. a couple boxes of good 500 NE ammunition would cost more then this entire test!

    -matt
     
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  4. Sako AV

    Sako AV AH Senior Member

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    As JimP stated, factory ammo is shot out of test barrels that are usually 24" rather than the 22" tube on your rifle. Without actually doing the math for each load listed it appears that they average @ 80 to 100 fps slower than advertised in your rifle. Most standard loads lose @ 40-50 fps for each inch of barrel shorter than the test barrel used to rate it from everything I've read so I would assume with a full 24" barrel most of those loads would be pretty close to their advertised velocity.
     
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  5. Tra3

    Tra3 AH Enthusiast

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    Interesting post, thank you.

    What chrono do you use? Were you able to test accuracy at the same time?

    Which of the rounds had the lowest standard deviation?
     

  6. One Day...

    One Day... GOLD SUPPORTER AH Fanatic

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    In 2015 I thought that the article .308 Win Barrel Cut-Down Test: Velocity vs. Barrel Length from Accurate Shooter was interesting:
    "The average velocity loss per inch, for all four ammo types combined, was 22.7 FPS."

    upload_2019-5-19_22-56-20.png

    So, going from 24" to 22" would reduce velocity by ~50 fps for a .308. It may be a tad different for a .270 Win but I would not think that it would be double ;)

    This being said, factory ammo clocking a bit slower than advertised is nothing new, although this has been a lot better since the broad availability of affordable chronos :whistle:

    An additional component, which I think is important to remember, is altitude.
    Air density drops with altitude, and it has a significant effect on both velocity and ballistics. I knew the theory of it, but I was flabbergasted when I moved from Connecticut to Flagstaff Arizona, which is at 7,000 ft elevation, to discover that virtually all factory ammo I have been clocking in Flagstaff actually EXCEED factory specs by ~20 to ~25 fps. I find it remarkable that 10 ft in front of the muzzle, where the chrono screens are, there is such a difference between 0 and 7,000 ft elevation. One can easily image the difference after 300 yd, which is the reason - hint! - why the serious ballistic software ask what the Density Altitude is when the rifle is zeroed, and what the Density Altitude is for the upcoming shot.

    There is still the possibility that my chrono gave up the ghost, and I have been wanting to clock with 2 different chronos for a while, but I observe that the actual ballistic curves of my .223 ,.308, .300 Win Mag Mk 11, 12 and 13 rifles out to 1,000 yd match pretty closely the software calculations, so I have to assume that the chrono is not too far off...

    This can have quite an effect actually on hunting. Last August I was at Huntershill in the Eastern Cape of South Africa and met a soon-to-become friend hunter from Spain who was wondering if his Blaser R8 had lost its zero. Turned out, after I asked a few questions, that he was sighted at sea level, and Huntershill's mountains top out around 5,000 ft elevation. Everything was shooting faster and flatter, hence a couple inches higher :)
     
    Last edited: May 20, 2019

  7. matt85

    matt85 AH ENABLER AH Legend

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    at first i was keeping tabs on SD but to be honest i found this had very little impact on accuracy. Hornady had the best SD at 18 fps but shot much worse then the Barnes LR which gave me an SD of around 50 fps.

    as far as accuracy, i havent tested all of the ammunition yet. so far the winner is Winchester Deer Season XP (around 1.5" at 100 yards) but im only half way through.

    chrono is a Competition Electronics ProChrono. ive been using these for years and have been very pleased with them.

    you would likely need a 26-28 inch barrel to get closer to advertised speeds for most of these loads.

    -matt
     

  8. Alistair

    Alistair AH Veteran

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    Yeah, this gels with my own .270 experiences. I have a 22" barrel, and shooting at 1000ft or so at 18 degrees centigrade (don't know wht this is in F) I clocked all my rounds at around 120-250ft/s slower than advertised.

    My rounds were mostly cheaper plinking stuff, but I looked at PPU, Winchester, Federal, Remington, Hornady, Sako all in 130gr guise and nothing broke 2950, despite every box claiming 3050 without fail. Best I think was the Hornady whitetail stuff at around 2930ft/s, with the rest at between 2850 and 2900. SD was between 20fps (Sako) with the worst about 80fps. All except the PPU shot MOA though, which was quite gratifying. I've hunted with the Federal and the Remington and the deer didn't seem to care much either.

    Far as I can tell they get the tightest 24" factory barrel they can find, shoot it at a couple thousand feet on a hot day and then call that figure out on the box. The drops given on the box are shall we say 'optimistic' as well, even when one adjusts the velocities accordingly.

    I think the worst I've seen though is figures for the 6.5x55swede, all of which seem to be tested with 26 or even 28" barrels. Why I have no idea.
     

  9. bruce moulds

    bruce moulds AH Elite

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    standard deviation (s.d.) is usually 1/3 to 1/4 of extreme spread (e.s.) for 10 shot strings.
    s.d. is an irrelevant number for less than 10 shot strings, as it is a statistical measure, and requires at least 10 to be meaningful.
    sometimes in a string you can see s.d. becoming smaller, and sometimes bigger.
    an s.d. of 50 is really bad, as it means an e.s. of 150 to 200 fps.!
    bruce.
     

  10. matt85

    matt85 AH ENABLER AH Legend

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    this test wasn't looking for SD, it was simply done to get an idea of average velocity of each cartridge so I could correctly predict drop. I went into this knowing velocities would not be as advertised since the velocity on the package is more of a sales gimmick than actual useful information.

    I shared the speeds because I figured I could save other people the time and money. if you have a 24" barrel then you can expect to get about 50-70 FPS faster then my 22" barrel.

    -matt
     
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  11. flatwater bill

    flatwater bill AH Elite

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    Hornady SuperP was sure a screamer.............thanks for the post...............My 270 has a 22.6 inch bbl and gets 2940 fps from my handload............FWB
     

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