Question about "Inherent Accuracy"

[BigCheese1]

So I have read a lot of info lately and I often come across the statement that one cartridge has more inherent accuracy than another. My question is... how the hell is one "more accurate" than another?
It seems to me that ACCURACY is directly related to REPEAT-ABILITY. If a bullet comes out of the barrel and does somersaults and back flips and swerves around... but does that every single time.. you have an accurate rifle, do you not? You can know right where the bullet will be at any distance and still shoot just as accurate as a bullet that flies straight.
With todays incredible technology and gunsmiths, our rifles are made damn near perfect. The rifle is hardly ever the problem. So I am curious what others have to say about a 6.5 CM having more inherent accuracy than a 30-06? (Just an example)
If the same thing happens every single time... how does one bullet win the accuracy argument?

I do not mean to sound condescending but every time I hear "inherent accuracy" I scratch my head.

Lets hear it guys!

 

[MoBoost]

Inherent accuracy is the term that is used by magazine writers that don't know anything about accuracy or inheritance.
Most of the time it means a metallic cartridge using smokeless powder and a spitzer bullet.
On the other hand there are benchrest shooters that believe that if it is not PPC it's not accurate.
I am sure there is middle ground somewhere.

The way I see it - there is a certain form factor to the cartridge that attributes to the accuracy: 30deg shoulder, minimal body taper, long neck, small primer, etc .... Of course this way 308win becomes inherently inacurate - and that just chaps too many bottoms.

 

[BigCheese1]

The way I see it - there is a certain form factor to the cartridge that attributes to the accuracy: 30deg shoulder, minimal body taper, long neck, small primer, etc .... Of course this way 308win becomes inherently inacurate - and that just chaps too many bottoms.

Great response moboost. But lets say it had a 5 degree shoulder and tons of taper with a short neck! If every round you ran through your rifle was the same.. As most reloads are! Then would you not be shooting through the same hole every time?

I am becoming more and more confident that lots of guys are simply hung up on their favorite round or the new Tacticool ammo or rifle.
Yes, some guys flinch with more recoil so a .50 cal might throw you off more than a .223. But to say one cartridge is more accurate or possesses more inherent accuracy than another is asinine!!!
I do see how accuracy can be thrown off with a partially full case of powder though. My 270 ammo sounds like a half full salt shaker. This can result in inconsistencies.
But I will stand by my observation that ACCURATE rifles are REPEATABLE rifles.

Or in other words... Your 6.5 CM is NOT more accurate than Billy Bobs 30-30. It simply provides more precise repeat-ability.

 

[MoBoost]

Great response moboost. But lets say it had a 5 degree shoulder and tons of taper with a short neck! If every round you ran through your rifle was the same.. As most reloads are! Then would you not be shooting through the same hole every time?

No it won't.

Entropy is a bitch.

 

[BigCheese1]

No it won't.

Entropy is a bitch.

In regard for a viewers... would you care to elaborate?

 

[Diablo]

Presume he is indicating that the situation has far more complexity than your simple statement considers. A few examples are case volume consistency, primer inconsistency, powder burn rate inconsistency, bullet tension, seating depth variations, and on, and on, etc.

So, even when you do your best to produce consistent loads, there is still some randomness (is that a real word?) to consider that may affect accuracy. And we have not even discussed the rifle and trigger variations shot to shot, or the human element.

 

[MoBoost]

A few examples are case volume consistency, primer inconsistency, powder burn rate inconsistency, bullet tension, seating depth variations, and on, and on, etc.

Actually we have control over those things. Entropy - we don't.
Entropy states that thermodynamic system will go to the maximum disorder without intervention.
The burn itself is a chaotic and random event - the only thing we can do is to minimize the order of already existing variables - volume of the case, taper of the case, edges, length to diameter ration, etc. We can also control how somewhat random pressure is applied to the back of the bullet by the angle of the shoulder and length of the neck.


The future of accuracy lays in bypassing entropy all together - aka electromagnetic guns.

 

[scudzuki]

The controlled chaos that is the ignition of the smokeless powder in a metallic cartridge must to some degree be influenced by the shape of the cartridge interior.

Look at all the advances that have improved efficiency in internal combustion engines via changing the shape of the combustion chamber.
Modern gasoline IC engines have lens shaped combustion chambers that result in far more complete combustion of the fuel. Ideally the chamber would be close to spherical but that is not a realistic shape given the need to compress the fuel/air mixture, so instead combustion chambers are shaped like flattened spheres.

For the same reason, I imagine cartridges with a lower length to diameter ratio (like BR cartridges) would be more conducive to efficient and uniform combustion (and resulting pressure wave) of the propellant than those with higher length to diameter ratio, like the 30-06.

But it's just a guess.

Joe

 

[JRWALLSIII]

I like to tinker with all different cartridges. I believe that some cartridges are inherently more accurate than others based on my experience.

You can touch on efficiency, quality of brass, combustion. Or a number of other things.

I believe that a rifle built right with a great barrel should shoot numerous loads great no matter what the caliber. BUT From what I have played with some cartridges are just easier to get to shoot in the low .1s or even .0s at 100 and a cartridge that does that will show you just how crazy accurate a rifle can be at 1000.

A 6BR, 6 Dasher, and 6.5x47 all fit this category. Maybe it's because they were all using Lapua brass that had been BR prepped. Maybe it's luck (I doubt that).

I feel that most smiths and shooters will tell you the same. It's not snake oil and magic. I know that my smith builds and shoots just about every rifle that leaves his shop. There are ones that shoot in the low .2s or less 99% of the time with a load that had worked in past rifles. So load development was minimal. Other cartridges are finicky and need lots of load development to shoot to that standard of .2 or less.

Believe what you want about inherent accuracy.

I will now save you thousands of dollars......"Talk to your smith and see what he recommends and why based on your shooting discipline. More than likely he will be very knowledgable and is in the business to steer you in the right direction. Not just on cartridge selection but components as well. Buy once cry once. Also buy what works the very first time. You will save lots of time and money that way

 

[weshowe]

Gents,

I would agree that accuracy and repeatability go together. With out repeatability accuracy goes out the window. I won't do any good if your rifle will shoot 1/4 groups if it doesn't do it in the same place every time...without fail.

I'd opine that the rifle, shooter, and ammunition are all part of the "system" any part of which, if it fails, will cause failure of the whole.
So, the shooter trains his keester off, buys/builds the best rifle system he can afford, and reloads or buys quality ammunition in the hopes that it all comes together on the range. Inherent accuracy is not just one thing, but the parts of the whole honed to perfection. Personally, I'm not sure it's obtainable because shooters have off days, rifles break-get dirty-etc, and ammunition is subject to the elements-storage considerations-and what not. All "inherently accurate" is that we hope all elements come together in a consistent manner day after day.

Oh, it helps if the stars align, too.

Wes

 

[Pointman308]

I think the reason bench rest shooters use the PPC is because of all the things that you have all talked about it seems to be the most accurate. Thus making it the most "inherently accurate" round.

 

[Pinecone]

Considering I have met people with PhDs in internal ballistics (they deal with primer strike to bullet leaving the muzzle ONLY), there is a lot of things that affect the simple fact of the bullet leaving the muzzle.

BTW, I have also met those with PhDs in external ballistics (from muzzle to target) and terminal ballistics (from the tip hitting the target to the final affect).