velocity vs accuracy in long range shooting

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by wisdeerkiller, Jul 29, 2012.

  1. wisdeerkiller

    wisdeerkiller Active Member

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    so my question is how accurate do you need to be for shooting long range?(1000-1300yds)

    my gun is a remington 700 sps varmint in 308. (1 in 12 twist).

    i am shooting 168gr sierra HPBT with RL-15 powder.

    shot through my chronograph.

    these are at 100yds.

    the center group is 42.5gr at 2400fps and is .95".

    the bottom left is 43gr at 2450fps and is the best group at .425".

    the upper left is 43.5gr at 2500fps and is .815".

    the upper right is 44gr at 2550fps and is 1.11". (MAX LOAD IS 44.8gr)

    the bottom right 175 SMK at 44gr at 2475fps and is 1.45"(MAX LOAD IS 44.3gr)


    If accuracy is the way to go i should go with 43gr of powder but velocity is only 2450.

    50fps is about 2 foot difference at 1000yds.

    would like to switch to 175gr buy have 300 rounds of 168gr right now.

    any suggestions what i should do?

    thanks in advance.
     

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  2. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Best thing I could tell you would be to get off paper at 100 yards and move out to longer ranges doing practical field practice. That is when you go to an area where you can spot shots of opportunity, such as a very small, well defined rock, range it, dial up or hold over your shooting solution, set up for the shot and shoot as you would in the field at a big game animal.

    Record your shot placement, hit or miss and if miss, by how far you missed and what direction.

    Move to another range target, repeat and again, record your impact.

    Do this at varying distances and then take your impact data and compare it to the drop chart to see if you can tweak the drop chart to match up better with your rifles trajectory.

    Tweak your drop chart and head back out to the range and retest. Continue until your drop chart matches up perfectly with your rifles actual trajectory.

    Again, more of my opinion, groups are fine but they mean very little to the long range big game hunter. They tell us if we have a good consistant load but 100 yard groups tell us very little about a rifles long range performance. I have seen many rifles that shot well at close range that did not perform worth a darn at long range. I have NEVER seen a rifle that shot well at long range NOT perform well at close range!!!:)

    As far as what is more important to long range shooting, velocity or accuracy, simple answer is both. Velocity however is useless without accuracy so you want as much velocity as is safe and your rifle will accurately handle but if it degrades accuracy, a bit more velocity is not worth it.

    If you have one load that shoots 1 moa at X fps and another load that shoots 1/2 moa but is 75 fps slower, take the 1/2 moa load, 75 fps means nothing at long range if your consistancy is degraded.

    Again, test at long range. I have also seen many rifles that grouped 3/4 to 1 moa groups at 100 yards that shot into the 1/2 to 3/4 moa group size at longer ranges. This is not typical with the lower intenstity chamberings such as the 308 but with any long range bullet, generally they tighten up in moa group size as shooting range increases.

    Back to my main point, find a good load and get off paper and onto practical field practice shooting instead of punching paper groups. Your rifles barrel will last much longer and you will have much more fun with your rifle and learn much more about long range shooting as well.
     

  3. Muttt

    Muttt Well-Known Member

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    I've worked up a very similar load using 168 gr bullets. I use AA2520 instead of RL15. Anyway, I found two distinct accuracy nodes. The first was very near minimum. The second was right at 42.7 gr. The max for this load is 44 grains. As I went higher in the load (closer to max) I lost accuracy. The higher velocity meant nothing if I couldn't group well. So, I went with lower load. It chrono's at about 2660, which is only about 40 fps below the 2700 that factory hornady match will give you.

    Go with accuracy and not the highest velocity.
     
  4. bigbuck

    bigbuck Well-Known Member

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    When I first started out ,I was shooting at 100 yards and some guys on this site told me I should move out to 200 Yards. To see what my load was doing @ 200. Once I got a decent load at 200 I checked it at 300 (if your scope will allow). I believe a person could stop at 200 and then go out . but I would shoot at paper as far as I could. Paper tells you exactly whats going on! Then I would do exactly what Kirby has mentioned. Just my opinion.

    if you can get a load that shoots 1 1/2 @ 200 then you should be good to go.
     
  5. Greyfox

    Greyfox Well-Known Member

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    A lot have good points have been made. Something else to consider, particularly since you are speaking about 1000+ yards, is the 168 SMK. The bullet design, while sufficient for 700 yard work, is not the best design for the longer ranges due to the bullet profile, particularly the boat tail. This is pointed out in Litz's book. For the longer ranges I think you should go with the 175 SMK, or try one of the VLD designs. Not only will the be more stable/accurate, but as you point out, due to the higher BC, will catch up with the lower BC bullet at long range. Since you have a supply, if need be, they would sell quickly on this site, they are a great mid range bullet. I personally set an accuracy goal of .5 MOA or better, with much of my final testing done at a 500 yard range after initial results at 100/200 yards. I get best results with 43 gr. of Varget with 175's at 2550 FPS out of my MilSpec. 2700 FPS with 44gr of Varget with 168 gr. Both shoot .5 MOA or better with and ES of 5-15 FPS. I have found Varget to be very temperature stable.
     
  6. Bart B

    Bart B Well-Known Member

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    Most cartridges shoot most accurate at all ranges with reasonable muzzle velocities; not the highest attainable with some slow powders. And some loads producing the lowest spread in muzzle velocity and peak pressure are horrible in the accuracy department.

    I've suggested that one decide what the furthest they want to miss their point of aim at a given range, then find the rifle and ammo that they can shoot groups twice that size. If you max miss from point of aim at 800 yards is 5 inches, then use something you can shoot no worse than 10 inch groups at 800 yards.

    Extruded powder's been the favorite of long range competitors; ball powder's never been popular with the winners and record setters. Milder primers often produce better accuracy than the hot ones. And use bullets a few ten thousandths inch larger than your barrel's groove diameter.

    Shoot enough shots per group so that the groups are meaningful; one 20-shot group's about 10 times more meaningful than five 4-shot ones, four 5-shot ones or even seven 3-shot ones. Ignore the smallest groups shot; they happen the least often and folks typically wear out their barrels trying to shoot another tiny one they did months earlier. Accuracy you can count on all the time with a given load's best represented by the largest group shot with it.

    A favorite load for 24 inch 1:12 twist .308 Win. barrels at long range was 44 grains of IMR4320 under a Sierra 190-gr. HPMK match bullet. If your barrel's groove diameter is .3080" or smaller, it'll probably do well with this load. This assumes the barreled action is properly epoxy bedded and the stock screws are torqued to about 45 inch-pounds. And the barrel's got a good quality bore.

    Other successful loads at long range for the .308 round with a 1:12 twist barrel....43 grains of IMR4064 under a 175 or 180 grain match bullet.
     
  7. mrbigtexan

    mrbigtexan Well-Known Member

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    i personally will always shoot the fastest load that hangs under an inch, even if its not the most accurate. a suggestion is to try different seating depths and see if you cant get a faster, more accurate load. on a different note, i always thought 168 gr. bullets was max for a 1-12'' 308 barrel?
     
  8. Majopikeras

    Majopikeras Member

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    I think there are teo important things to consider...

    First, talking about speed, the distance where your bullet falls from supersonic to subsonic. Maybe 1k+ is too long for the 2450 Load... I haven't calculate it.

    Second, keep in mind the bullet energy and performance at those ranges. You are talking about hunt game, not punching paper or hitting stones. Yor rifle, load, bullet, scope and, of course, you, should be able to hit the animal and kill it as fast as possible. Hitting a deer on the butt and make it hurt and run away is an insane idea.

    Hope you can understand my english... Sorry for the mistakes!
     
  9. royinidaho

    royinidaho Writers Guild

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    You'll save time, money and barrel life and be a more consistent shooter if you do what Kirby said.

    Keep in mind that a 1.5 MOA system including rifle, shooter and environment places shots only .75 MOA from center. The trick is to know which direction from center.:)
     
  10. wisdeerkiller

    wisdeerkiller Active Member

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    with the max wieght for 1 in 12" i've seen that 175 are good and above that are hit and miss with different barrels
     
  11. wisdeerkiller

    wisdeerkiller Active Member

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    thinking about testing the 175gr SMK more but before i do, has anyone tried the 155 gr. Palma Match? B.C. is .447 and above 2900fps.

    Suppose to be as good as the 175SMK.

    Also my bullets are seated just off the lands not sure how much.

    how can playing with the seating depth add or decrease fps? i understand the accuracy part of it.




    SCOPE IS Mark 4 6.5-20x50mm LR/T 1/4moa.
     
  12. Bart B

    Bart B Well-Known Member

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    The big difference in barrels is their length. They gotta be long enough to shoot 180-gr. and heavier bullets fast enough to remain supersonic at long ranges.

    In the 1960's, the US Army Rifle Team replaced the 172-gr. match bullet in M118 7.62 NATO match ammo with a Western 180 gr. FMJ match bullet or a Sierra 180 HPMK bullet; sometimes adding a half grain of powder to what was already used for the 172 grain ones. They shot it in their M14NM's 22 inch barrel winning lots of matches and setting records, too. That was a stout load but the M14NM's handled it very well.

    Folks have shot 200 grain match bullets from 26 inch .308 Win. barrels with a 1:11 twist and 220's with a 1:10 twist; winning matches and setting records doing it. David Tubb used a 28 inch long 1:8 twist barrel shooting Sierra 250-gr. match bullets out at 2150 fps; they were still supersonic through 1000 yards and shot sub MOA test groups at that range.
     
    Last edited: Aug 1, 2012
  13. Bart B

    Bart B Well-Known Member

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    As one of the Palma Team members who helped develop the first loads for that bullet when prototypes were given to us in early 1991, I can attest to its accuracy as I shot the high 5-day aggregate score in the first match it was used. It quickly became a favorite. 29 inch barrels are about minimum so they can be shot at least 2900 fps to remain supersonic through 1000 yards. After they were first used in a big long range match in late 1991, top long range competitors from around the world shooting them said they'd never shot bullets that accurate. A couple dozen of them told me they shot no worse than 1/2 MOA at 600 yards; not too shabby for new cases, metered powder charges with a 1/3 grain spread and bullet runout of up to 3/1000ths. Soon thereafter, that 155-gr. bullet was set as the standard for all long range matches shot under the International Palma Committee's rules. In the USA, the shooters handload those bullets. In other countries, they aren't allowed handloads and have to use arsenal ammo that's loaded with Sierra 155's in their big matches.

    The half dozen of us developing and testing loads were quite pleased with our work and since then, when IMR4895 was the powder of choice, Varget is now a better choice. And now there's a newer version with higher BC that's supposed to be better. I shot one test group in 1992 at 800 yards with the resultant load; 45.3 grains of IMR4895, Sierra 155 seated to touch the lands + .010", Federal 210M primer in a Winchester unprepped case full length sized: here's the 20-shot test group with shots 1 and 2 being the first two from a cold, clean barrel:

    [​IMG]

    The less jump to the rifling there is, the higher the muzzle velocity is. It doesn't change very much and some folks are hard pressed to tell the difference between 50/1000ths jump and zero jump. Pressure's also higher with shorter jumps to the lands. Sometimes one has to cut their charge by a grain if the seat bullets to jam into the lands when loaded, but that's typically what produces the best accuracy.
     
  14. Boss Hoss

    Boss Hoss Well-Known Member

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    First don't get twisted up about 25 fps or even 50 fps because your muzzle velocity spread if properly done will tell you a lot more and help you a whole lot more than that little bit of velocity.

    Lower muzzle velocity deviation means less vertical dispersion FACT do the math on your load and you will see what just 35fps will do high to low. Your group shooting is subject to too many variables to even go into here but we will assume you are set up perfect and your technique is perfect on the bench for you load evaluation.

    Groups at 100 yards mean squat at 1kā€”there is No correlation at all and if anyone tells you different they have never shot long range BR and been successful. To properly evaluate the pills you are using start at 300 or 400 if possible and go from there on development. When shooting LR consistency is the overall key to being successful. Being able to get the rifle and load to shoot the same every time THEN you can work on things like judging condition which is the single most important variable besides set up you will face in your quest.