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Thread: accuracy

  1. #1

    accuracy

    Do poeple think that a certain caliber is more accurate than the others, or are all calibers equal and its the rifle that makes the round accurate?

    steve

  2. #2
    The barrel and breeching will have an effect on precison. Having a poor barrel will certainly hamper any precision you hope to get likewise having a poor breeching set up. A barrel that's out of square with the breech face cannot help matters. It also seems that having the right loading density behind the bullet can/does effect precision in grouping. However with the correct bullet any calibre can be precise. The bench rest crowd seem to believe that short fat powder columns are the way to go and they worship on the alter of precision .

  3. #3
    There are certainly some cartridges that have gained a reputation for being inheritantly accurate - 22rf, .222, 6.5x55, 7x57, .308 spring to mind, in that most rifles chambered in these cartridges will tend to be fairly forgiving and will shoot most ammunition pretty well. A lot will do with the inherent harmonics / balance and proportions of such cartidges - often referred to as well balanced. High velocity, or higher pressure cartridges - eg 264 win mag, 22-250 or even the 243 have a reputation of being a bit fussy - they will shoot very accurately, but are often with only one or two particular loads.

    A lot will also do with the quality of the rifle itself and quality of manufacture - see Brit hunters comment above. eg the 6mm PPC is reckoned to be a very accurate calibre - but is this due to its inherent ballistics or that it is ony found in custom built varmint / benchrest style rifles? Probably a bit of both.

    And finally there is the shooter element - some calibres with a nice soft recoil are just easier to shoot and thus while they may be no more accurate than others you just have the ability to put the bullet in the right place, which at the end of day is what counts. To some extent this also true of the load. For example my 7x65R with a full power RWS loaded 173gn bullet at 2,800 fps in a lightweight rifle has a pretty sharp recoil - somewhat uncomfortable. Bt since I have developed a load with a 139gn bullet at c2,700 fps, plus lengthened the stock it is now really comfortable and easy to shoot. Nothing has really changed other than my perception of the rifle. Likewise the 270 did have a reputation of being quite a kicky calibre, albeit pretty accurate, but in these days of moderators, it is now an easy to shoot calibre.

  4. #4
    I shot the target below at 100 yds in 2007 when I was 74 using my Sako HB .243 with the loading written on the card.
    Using the 75gr V.Max bullet instead produced similar results but at a different impact point.
    Accuracy is a combination of a precision rifle, a compatible load, correct seating depth and of course the capability of the individual behind the trigger.
    HWH.

  5. #5
    Never forget the nut behind the butt...


    There are certain cartridges that are reckoned to be inherently accurate. I believe one of the major bullet manufacturers uses a .22BR chambering for it's .22 centrefire bullets due to this.

    6ppc is of course another and these both have short fat powder columns.

    That difference is not normally noticeable in the field but in out and out accuracy comparisons then the differences show up.

  6. #6
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    Vice nice group Stag1933.

    What was it like at 200 and 300yds ???
    What were the chrono readings and ES and SD ???

    I personally like to test loads at 200-300yds and run them over a chrono because I found that some loads that were really good at 100yds were pants at 200 and beyond. I get similar groups to yours above at 200 and 250 yds with 80grain bergers, but at 100yds it is a little bigger.

    I put it down to bullet stability but a 1 in 10 shooting a flat base 80 grain should stabilize very quickly.

    Figure that one out ???

  7. #7
    Quote Originally Posted by robbobsam View Post
    Vice nice group Stag1933.

    What was it like at 200 and 300yds ???
    What were the chrono readings and ES and SD ???

    I personally like to test loads at 200-300yds and run them over a chrono because I found that some loads that were really good at 100yds were pants at 200 and beyond. I get similar groups to yours above at 200 and 250 yds with 80grain bergers, but at 100yds it

    Figure that one out ???
    If the group is tight at 100m it can only get bigger at subsequent ranges. Like a click on your scope 10 mils @ 100 and 20 mils @ 200.

    If you have a tight group at 100 and not at 200 it would probably the the shooter.
    Last edited by Paul 600; 12-12-2010 at 11:27.

  8. #8
    Quote Originally Posted by robbobsam View Post
    ....What were the chrono readings and ES and SD ??? .........
    robbosam. Here's an interesting article on ES and SD.

    The Rifleman's Journal: Ballistics: Statistics for Rifle Shooters

    It's conclusion on ES is as follows:

    • ES is not a reliable statistical indicator
    • The best indicator of velocity variations is the standard deviation.
    • Most figures we read and hear about with respect to SD and ES have very little meaning…

    Rgds JCS

  9. #9
    My range has an excellent back-stop to 125 yards but as scope clicks are calculated for either 100 yds or 100 metres I use the distance appropriate to the scope used on that day. [ It is also easier to `spot` the shots at that distance.]
    I have a chrono but I rarely use it as I am more interested in small group size than maximum bullet speed.
    I have always been a close-range stalker and never a long-range sniper as I believe that even a humble rabbit or carrion crow deserves respect and not to lose a leg through my ego or incompetence.
    With the 1 in 10 twist Sako .243 and the 75gr V.Max or the 68gr Berger I set my rifle to shoot half-an-inch high at 100yds and had no problem with furry and feathered vermin out to 200yds or so.
    I did find however that the 68gr Berger had little or no expansion on carrions etc. and I had a few spectacular instances when a seemingly missed crow flew off and fell dead out of the sky after going 50-80 yards.
    For Deer I usually pick up my trusty .270 Carl Gustaf which is normally set to shoot an inch high at 100yds.

    I leave B.C. and S.D. etc. to manufacturers and `buffs` or cranks and use bullets designated as `fit for purpose` by the manufacturers.

    For mountain work where distances are greater and quarry size larger I set the .270 to shoot three inches high at 100yds.

    HWH.

  10. #10
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    Quote Originally Posted by jcampbellsmith View Post
    robbosam. Here's an interesting article on ES and SD.

    The Rifleman's Journal: Ballistics: Statistics for Rifle Shooters

    It's conclusion on ES is as follows:

    • ES is not a reliable statistical indicator
    • The best indicator of velocity variations is the standard deviation.
    • Most figures we read and hear about with respect to SD and ES have very little meaning…

    Rgds JCS
    I am always open to debate on a topic and will use logic and reason to support facts I quote.

    To say that the extreme spread is not important is a little concerning to me because the laws of physics dispute you.

    Example. (Figures from Exbal)

    A .308 180grain bullet at 2600ft/sec will drop 14.2" at 300yds
    A .308 180grain bullet at 2500ft/sec will drop 16.7" at 300yds

    (2.5" difference caused by velocity differential alone)

    If you add to this differential the effect of the wind, the normal grouping differential and the effect of nut behind you will quickly see how the grouping will start to enlarge quite dramatically.

    I try to keep my groupings as tight as possible and I find by keeping the velicities of my ammo as consistent as possible helps this.

    The most accurate shots in the world are the competition guys that shoot in the long range competitions, Whilst I would not want to shoot competitions myself I do read quite a bit from various F-Class forums and it appears that most of them observe the ES and SD very closely, therefore I assume this must be an important part of long range shooting and exbal supports this fact.

    However, I will concede that when you shoot at ranges up to 300yds the ES and SD doesn't have a huge difference when shooting at deer sized targets.

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