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.308 175gr factory ammo?

  • 18-06-2021 8:48am
    #1
    Registered Users Posts: 1,084 ✭✭✭ alanmc


    Hi all,

    Has anybody seen any .308 175gr factory ammo on RFD shelves? I'd love to try some. I have a 12" twist barrel and apparently there's a good chance I'll get good results from the 175gr. So far the 168gr Sako Raceheads I've been using are working really well when I don't balls things up. But I believe that they become unstable at the longer ranges (or is that just the SMK variant?).

    Thanks,
    Alan.


Comments

  • Registered Users Posts: 6,758 ✭✭✭ clivej


    alanmc wrote: »
    Hi all,

    Has anybody seen any .308 175gr factory ammo on RFD shelves? I'd love to try some. I have a 12" twist barrel and apparently there's a good chance I'll get good results from the 175gr. So far the 168gr Sako Raceheads I've been using are working really well when I don't balls things up. But I believe that they become unstable at the longer ranges (or is that just the SMK variant?).

    Thanks,
    Alan.

    I bought some Hornady match 308, 175gr yesterday in Red Mills in Kilkenny.
    I'd say you will need a faster twist than 1 in 12 barrel for those.


  • Moderators, Sports Moderators Posts: 27,534 Mod ✭✭✭✭ Cass


    I always found 168 SMK to be terrible past 300 yards, for target work. Drop quicker, unstable in flight and not as good to group. They're a stubby bullet and the 155 and 175 are longer including having a longer bearing surface.

    That is why some 175s work well in the 1:12 twist. The bullets OAL is longer than the 155, but the bearing surface is very close to the 155 (well some 155s, not all) and as the rifle only uses this to stabilise the bullet it explains why.

    As for seeing some, afraid not. Haven't been out to any RFDs in over a year, but even then I only saw 150, 155, 165, 168, 180s.

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  • Registered Users Posts: 1,084 ✭✭✭ alanmc


    So following on from above, if one were to be looking for a factory off the shelf round in .308 that would go to 800 or 1000 yards somewhat reliably and accurately, what would be suggested? Would the Hornady 155g ELD-Ms be a good shout? Bearing in mind the 12" twist of course.


  • Registered Users Posts: 6,758 ✭✭✭ clivej


    alanmc wrote: »
    So following on from above, if one were to be looking for a factory off the shelf round in .308 that would go to 800 or 1000 yards somewhat reliably and accurately, what would be suggested? Would the Hornady 155g ELD-Ms be a good shout? Bearing in mind the 12" twist of course.

    IMO....... I have shot my Sako 75 308 in competiton out to 600y using Hornady AMax 155gr, 2800fps, 1in11 twist. Wind was a bit of a problem on the day, but I managed to get a 9th place, this against the big boys on the day. This is where the 175gr head will do better, in the wind.

    From what I have been told the 155gr start to loose accuracy after this.
    I have just bought 2 boxes of Hornady 175gr EDL match to try and get out further. Don't know when I'll get to try these out yet.


  • Moderators, Sports Moderators Posts: 27,534 Mod ✭✭✭✭ Cass


    With 1:12 twist you really want to be staying in the golden spot for bearing surface length. Now most manufacturers don't give this, its a case of researching online, but the rule of thumb is usually 150 to 155.5. Some other rounds will work, like the 168, 175 or 178 gr, but then again you still need to know the bearing surface length.

    The Berger bullet stability calculator is a useful tool. I just done a quick comparison of a 155vld vs a 185 vld in a 1:12 twist and the 155 is stable, but the 185 is only marginally stable, bordering on unstable.

    This calculator does not give the option of inputting bearing surface length but as its a drop down menu selection I'd assume its already taken into account. It only has a limited choice of ammo, all Berger, but if you were to find out what was stable, what the bearing surface length is, then you can check other ammo and do a search for ammo with the same bearing surface.

    All of the above is only one aspect. This is why target shooting at up to 1,000 yards is so complicated. If you found the perfect round with the perfect bullet (factory) that is one battle. The next is consistency. While most ammo will perform within a certain margin there can be anomalies. Such as a round with a lower charge, not properly seated (imperceptible to the naked eye), or anything other of a dozen issues that will give you an unknown drop, flyer or other result that is not in keeping with the rest of the ammo you have.

    Of course if you've gotten to this stage then you're already down the Rabbit hole so might as well go the whole Hog, but if you just wanting something to plink with try a few different boxes of ammo within this golden ratio and see which performs the most consistently. Don't forget that some ammo does not perform well at shorter distances, and only comes into their own at longer distances. Found that out the hard way when trying out ammo at 100 yards only for it to be crap. Decided to fire of the rest at 800 yards (after zeroing for the distance) and found they worked wonders at 800 to 1000 yards.

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  • Registered Users Posts: 6,182 ✭✭✭ Feisar


    Cass wrote: »
    Don't forget that some ammo does not perform well at shorter distances, and only comes into their own at longer distances. Found that out the hard way when trying out ammo at 100 yards only for it to be crap. Decided to fire of the rest at 800 yards (after zeroing for the distance) and found they worked wonders at 800 to 1000 yards.

    Is that down to a BC advantage or the theory that some bullets need to "settle down", specifically VLDs.
    I know the cone of accuracy can't come in but disimproves less relative to distance.

    First they came for the socialists...



  • Moderators, Sports Moderators Posts: 27,534 Mod ✭✭✭✭ Cass


    Feisar wrote: »
    .........or the theory that some bullets need to "settle down", specifically VLDs..
    This was the only "answer" I could find at the time of looking. Brian Litz talked about it in one of his books. Something to do with the gyration effect of the bullet "settling" or decreasing over distance.

    In layman's terms (that I could understand) the bullet settles in flight over
    a longer distance. The other side was who am I to argue with Brian Litz. The man has forgotten more than I'd ever learned.

    Forum Charter - Useful Information - RFDs - Ranges by County - Hunting Laws/Important threads


    If you see a problem post use the report post function, "FLAG" & let a Moderator deal with it.


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