accuracy

musty

Well-Known Member
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
 
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 ;).
 
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.
 
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.
BUGGYCROWS048.jpg
 
Never forget the nut behind the butt...:D


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.
 
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 ???
 
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.
 
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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.
 
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.
 
Robbobsam, i find my .223 with home loaded 40gn BTs in it groups at 0.3 MOA all day long. Ive chronoed a fair few rounds and the ES is massive.. like 200fps different.. BUT the rifle still groups exceedingly well.. even at 200 or 300 yds. It seems that ES makes very little difference.

On the other hand, i had a rifle which the ES was 20-30fps and wouldnt group better than MOA.

I use the chrono to get a MEAN velocity for the calculator but thats it.

Im all with you on consistency throughout the process but my findings from the chrono show that there is no set correlation between ES and grouping.
 
Robbobsam, i find my .223 with home loaded 40gn BTs in it groups at 0.3 MOA all day long. Ive chronoed a fair few rounds and the ES is massive.. like 200fps different.. BUT the rifle still groups exceedingly well.. even at 200 or 300 yds. It seems that ES makes very little difference.

On the other hand, i had a rifle which the ES was 20-30fps and wouldnt group better than MOA.

I use the chrono to get a MEAN velocity for the calculator but thats it.

Im all with you on consistency throughout the process but my findings from the chrono show that there is no set correlation between ES and grouping.

Hiya flyingfisherman

I do not disbelieve what you are saying and I am sure you can hit 0.3MOA all day and thats great shooting, but for you to do that and do it at 300yds and still maintain an ES of 200ft/sec is just not possible.

0.3MOA is equal to sub 1" groups at 300yds and that is top class shooting.

The 0.3MOA is very possible
The 0.3MOA is very possible and is fantastic shooting btw well done.
But .3MOA at 300yds and an ES of 200 is just not possible, as it goes against the laws if physics.

Please feel free to check your drops on here http://www.biggameinfo.com/BalCalc.aspx or here http://www.winchester.com/learning-center/Pages/Ballistics-Calculator.aspx

I have made a few quick calculations with estimated velocities and BC's and the ES of 200ft/sec will give you a differential drop of 2" minimum. This would make .3MOA pretty much impossible.

I think your Chrono must be out. Bear in mind that most Chronos will only be accurate to 1% which is 30ft/sec differential before we start.

I think that in order for your chrono to generate those figures with such fantastic groups your chrono is out quite badly.

If you are ever in the midlands please feel free to look me up as I will willingly let you use mine.
 
This was THE 10 shots through the chrono, 5 @ 100 and 5 @ 300.


To clarify, i dont shoot 0.3 all the time, sorry, but the rifle is well capable of it. Im seeing 1'' groups at 300yds on a good day ie no wind, me not having the shakes etc! On a bad day at 300yds im seeing 2-3'' groups which is obviously closer to MOA, but if the rifle will shoot sub 0.5 at 300 the the ammo on the right day with the ES of 200fps then it proves that ES isnt everything.

1: 3492
2: 3528
3:3460
4:3533
5:3471

6: 3654
7: 3541
8: 3618
9: 3478
10: 3601

On a note, what i did see is that certain powders give better continuity RE speed. in the .223 i tried H4895 which is very uniform with velocity opposed to the H335 which gave me the above results.
 
This was THE 10 shots through the chrono, 5 @ 100 and 5 @ 300.


To clarify, i dont shoot 0.3 all the time, sorry, but the rifle is well capable of it. Im seeing 1'' groups at 300yds on a good day ie no wind, me not having the shakes etc! On a bad day at 300yds im seeing 2-3'' groups which is obviously closer to MOA, but if the rifle will shoot sub 0.5 at 300 the the ammo on the right day with the ES of 200fps then it proves that ES isnt everything.

1: 3492
2: 3528
3:3460
4:3533
5:3471

6: 3654
7: 3541
8: 3618
9: 3478
10: 3601

On a note, what i did see is that certain powders give better continuity RE speed. in the .223 i tried H4895 which is very uniform with velocity opposed to the H335 which gave me the above results.

As I said above, with the chrono readings you quote above 300yd 0.3moa is just not possible, alternatively the chrono is inaccurate.

Personally I think its your chrono.

You cannot argue with the laws of physics.
 
As I said above, with the chrono readings you quote above 300yd 0.3moa is just not possible, alternatively the chrono is inaccurate.

Personally I think its your chrono.

You cannot argue with the laws of physics.

Hi Robbosam and Flyingfisherman
You have totally lost me i aim my rifle at deer/fox /rabbit him fall down =good shot, him not fall down=bad shot, him fall down get back up=good boy go find
Geordie
 
Hi Robbosam and Flyingfisherman
You have totally lost me i aim my rifle at deer/fox /rabbit him fall down =good shot, him not fall down=bad shot, him fall down get back up=good boy go find
Geordie

Geordie I like your rational :D:D:D:D:D:D

I am just a bit anal about accuracy. I tend to shoot at extended ranges and in order to do it well I have to get things spot on.

If my ES and SD are too high I cannot shoot at extended ranges as the groups open up too much.

Up to 300yds it doesn't really make much difference.
 
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Up to 300yds it doesn't really make much difference.
I know where you are coming from with that!,........ He's laying on the .223, I'm picking up the bunnies with the Geovids,........ I made my call on the wind, he alters his p.o.a............. dead bunny! 450yards head shot.
 
ive just been out again with the .223 as it was a nice avo, shot a 3 round group at 200 yds and it measured 1/2 inch CtC which is 0.25MOA. I shot a 5 round group at 300yds and it was 1.20'' CtC. Which would be 0.38MOA.

I didnt chrono them though, may do that tomorrow.


Oh, georgdieH, i liked ur post! I need to have an accurate rifle to make up for me! lol
 
View attachment 3812
I am always open to debate on a topic.......

robbosam. All ES tells you is the difference between the fasted and slowest velocity. It tells you nothing about the distribution of the intermediate velocities. Just because it's easy to measure doesn't mean that it is useful. The Standard Deviation is a much more useful number. The article is well worth reading again.

With my own loads I am aiming to get an SD of 10 or less.

Rgds JCS
 
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View attachment 3812

robbosam. All ES tells you is the difference between the fasted and slowest velocity. It tells you nothing about the distribution of the intermediate velocities. Just because it's easy to measure doesn't mean that it is useful. The Standard Deviation is a much more useful number. The article is well worth reading again.

With my own loads I am aiming to get an SD of 10 or less.

Rgds JCS

I did manage to get a spread of 8fps once but it was not as good as the group with 48fps spread.
These were 5 shot groups with identical ingredients other than the primer.
Brass had been weighed for consistency and powder charges dropped and trickled for precision.
Both were shot with my Sako HB .243 in succession.
For some reason unknown to me I have never had a tight group using the BR2 primers.
HWH.
BUGGYCROWS049.jpg
 
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