What exactly is "inherent" accuracy in regards to a cartridge?

[Stumper]

There are lots of good responses in this thread (and some which I think are off base). Since a comment of mine inspired this thread I snagged my response to the question from over there to help show where I was coming from.

"460, You are correct that the individual firearm is critical to accuracy. With a given firearm their will be some specific loads that shine.When speaking of "inherent" accuracy of cartridges/chamberings we are talking about planned design criteria(such as the PPC rounds) or happy coincidences that make some cartridges "easier" to achieve a high degree of accuracy. This doesn't mean that a particular firearm and load of a not particularly"inherently accurate" cartridge can't trounce lots of the "inherently accurate" chambered guns. However some chamberings are known to be very non-critical regarding bullet weights and powder charges to achieve accuracy. Other cartridges have a deserved reputation of being difficult or even exasperating. For instance the 32-20 that I mentioned-There are guys who have shot beautiful tight groups with a 32-20 revolver...but the same gun, same brass, same bullet weight and a different powder loaded to achieve similar velocity scatters shots all over the paper. OTOH most decent .38 specials will shoot reasonably well with any load and spectacularly well with some. It is an easier/more inherently accurate cartridge. The 9x19 is a tremendously efficient cartridge (small charges for top performance) and is not problematic in achieving adequate accuracy for most purposes.....but it is harder to get it to shoot all the bullets through the same hole than a .38 special or a .45 ACP."

 

[MachIVshooter]

Lots of gobbledygook getting thrown around here. If you build the rifles the same way, load the ammo the same way, and use the same quality of components then it won't matter what cartridge you shoot.

There's a lot more to it than that. Less posting and more reading, my friend.

I'm really curious why.
Are they (30-06 and 308 win) firing the same exact projectiles with the same rifling twist in the same actions, with the 308 proving out to be such a demonstrably more accurate round?
Would that then be a function of that particular projectile being better suited at the 308's velocity range than the 30-06's velocity range or 308 + 150fps?

Again, it's that the shorter and fatter powder column of the .308 gives you a more consistent burn with a wider range of powders. The .30-06's larger case capacity with a slightly narrower column at the front is going to be more powder type and charge weight sensitive to get that burn uniformity. Using powders that completely fill the case or even compressed loads help, but again, there are more powders that accomplish this in the .308 case than in the .30-06.

Consistent burn equals consistent pressure, which in turn equals consistent velocity. Consistent velocity means that the bullets will all land in the same place if environmental factors do not change.

Precision is consistency, period. That's why we buy expensive match brass and then weigh cases and turn case necks to ensure that it is uniform to tenths and has uniform neck tension, buy quality bullets and then weigh each one, grouping them for loading into batches by 0.1 grain weight differences, use expensive primers that have higher quality control to ensure that the cups and anvils are as close to perfect as possible with a very exact amount of compound evenly distributed in the cup, weigh each charge of powder to within <.1 grain and only use one lot for a batch of ammo, seat bullets to exactly a specific distance off the lands using micrometer seating dies, etc.

 

[David N]

Is there something wrong with the .243 Win cartridge? There are several references here that seem to cast it in a bad light.

 

[Zaydok Allen]

While I can see how the same concept would apply to a pistol cartridge, is there any practical application to handgun cartridges? I mean I would think that the distance to target would need to be loooong in order for this to have any measurable impact on pistol shooting.

That doesn't negate the concept or truth behind it. I will have to accept other's words here as I have no real frame of reference. I mostly only shoot pistols and not rifles.

 

[george burns]

I think it's the shooter that inherently accurate, like Kyle was, with just about anything.
I know several guys who can't hit anything that think they are accurate enough to judge the firearm.

 

[Nom de Forum]

Is there something wrong with the .243 Win cartridge? There are several references here that seem to cast it in a bad light.

There is absolutely nothing wrong with the .243 Winchester!

It is one of the finest of hunting cartridges.

It was never my intention to give the impression I think there is something wrong with this cartridge. I was merely using it for an example because it shoots the same diameter bullets the 6mm PPC uses. Even if you used the very best components available and the most stringent of precision handloading techniques it is not going to be something you would chose over a 6mm PPC for the very highest level of accuracy in benchrest competition. I do believe some people did chose the 6mm PPC for hunting because SAKO at one time offered it in a hunting rifle.

 

[Nom de Forum]

I think it's the shooter that inherently accurate, like Kyle was, with just about anything.
I know several guys who can't hit anything that think they are accurate enough to judge the firearm.

Shooting is the easy part of being a sniper. Go to Sniper school and I guarantee that the shooting will be the easiest skill you need to demonstrate to graduate. No offense to Chris Kyle but he was not when alive considered the best precision marksman in the World. Snipers do not have to be the best marksman in the World and do not make up the majority of shooters who are. When you start discussing the level of marksmanship that requires procedures that MachIVShooter listed you are way past the Sniper level of ammunition selection.

 

[jmr40]

Cartridge shape plays a role. It has been pretty well proven that shorter cartridges burn powder more efficiently than long cartridges which results in more consistent velocity from shot to shot. Bolt rifles built on short actions are stiffer than long actions. As a net result the 308 will always have the potential to be more accurate than 30-06. The same applies to other cartridges as well. There is overlap, not all 30-06's are more accurate than all 308's, and not all shooters are good enough to take advantage of the difference. But there are some cartridges that are more "inherently" accurate than others.

 

[rbernie]

I've always assumed that the 'inherent' part was related to the ability of the cartridge design to support repeatable and consistent burns and facilitate repeatable and consistent manufacturing.

 

[taliv]

dont' forget the difference in large and small primers, which is why 308palma brass exists and why most benchrest cartridges have small primer pockets

 

[tipoc]

From 460Kodiak,

While I can see how the same concept would apply to a pistol cartridge, is there any practical application to handgun cartridges? I mean I would think that the distance to target would need to be loooong in order for this to have any measurable impact on pistol shooting.

This is a good question and I'll take a whack at it. I think we can go back to a question raised about Elmer Keith earlier to illustrate.

Keith began experimenting with the 45 Colt. But, to make a long story short, the guns of the time were not strong enough for what he was trying to do and he moved to the 44 Special which had more meat in the cylinders. He was handloading for both. Keith praised the accuracy of the 44 Special in relation to many other rounds.

The case for the 45 Colt comes from the blackpowder era where when you wanted more power you got a bigger bullet, a larger case and more powder. With the development of smokeless powder (and more efficient powders at that) the case of the Colt is large to accommodate this. The case for the 44 Spl. straddles the blackpowder/smokeless era and has less capacity. This meant in practice that the powder in the 44 burnt more evenly. Keith got better accuracy from the 44 Spl. especially after his innovations in bullet design. The 44Spl. also has a slightly better ballistic coefficient but that is of minimal influence in handgun shooting.

Now there were other reasons besides this that were factors in the accuracy of one over the other (balloon head brass, the guns, etc.). The time Keith was working was also a factor. There have been improvements in many areas since then. But this remains a factor with the 45 Colt. Mike Venturino and John Taffin, in their books and on Taffin's website has discussed this a number of times from various angles.

Venturino and others have opined as they don't see any real accuracy difference between the 44 Spl. and other rounds. Maybe not now and maybe not at the distances handguns are typically shot at.

But the basic point you raised is I think true. You don't really see the difference as often in handguns as in rifle. Because at typical handgun ranges the difference is minimal. This is also because it is harder to shoot handguns well at longer distances and the shooter and gun are often bigger factors than the ammo.

tipoc

 

[Zaydok Allen]

Thank you tipoc! I was hoping someone would notice me waving my arms around. I'm learning a lot from this thread, and find it a very interesting topic. Knowing little about rifle cartridges and how the construction really influences the accuracy and ballistics, this is a concept I did not really grasp until now.

I'm curious if stumper feels differently on the pistol cartridge side of things.

 

[Stumper]

I don't really think differently on the pistol side of things as far as charge shape etc having an influence.....but hyper accuracy has never been as much of a factor in handgun shooting.(The popular pistol games are more a test of the shooter and a level of moderate precision at great speed. Bullseye pistol and Silhouette shooting both require accuracy....but not like rifle benchrest competition where 100 yard groups need to measure in small fractions of an inch to win. Bottleneck cartidges in handguns have usually been seen as more trouble than they are worth(but, ironically the ones that have succeeded have utilized some of the PPC principles such as minimal body taper and sharp shoulders in contrast to the utter failures like the .22 Jet which had a lot of taper and a sloping shoulder and tended to tie up the gun!) Many of the "accurate" handgun cartridges predate smokeless powder and have "excess capacity" yet they still are easy to achieve accuracy with. The excess capacity actually probably works in the favor of oldies like the .38 and 44 Specials because they are low pressure rounds and the larger combustion space means bigger charges of fast powder and less influence from minor changes in seating depth-In contrast the 9mm Parabellum is an ultra efficient military cartridge. With its limited capacity and tapered case it has proven very reliable in combat and defensive arms and despite its great age is thoroughly "modern"......but that limited capacity and tapered case fight against ultra precision. Adequate accuracy for military use and plinking isn't difficult but it requires more effort to get tiny groups from the 9. Even the straight walled cases begin to show a drop in "ultra accuracy" as they have been lengthened into magnums and "maximums". (It isn't a pronounced or extreme effect but those who have tested such things note that a .357 maximum seldom achieves groups as small as can be obtained in the same firearms when chambered for the .38 special.Likewise the.357 mag doesn't do badly but it tends to lag behind the .38spl. Leaving aside recoil and muzzle blast (which definitely effect MY shooting), a Ransom rest tends to confirm that super accurate loads are harder to achieve with the longer case......perhaps this is due to the ratio of diameter to length just as seems true in rifle cartridges. The .44 mag has tended to shoot really small groups from machine rests.....but it is a lot fatter than the .357.
For me and 99%+ of shooters this is mostly just interesting but irrelevant. I'm not a benchrest shooter or a bullseye target pistolero. I like to plink and hunt. I don't like inaccurate firearms but so long as the gun shoots better than I do under field conditions I'm happy.....and most of them do.

 

[SilentStalker]

Shooting is the easy part of being a sniper. Go to Sniper school and I guarantee that the shooting will be the easiest skill you need to demonstrate to graduate. No offense to Chris Kyle but he was not when alive considered the best precision marksman in the World. Snipers do not have to be the best marksman in the World and do not make up the majority of shooters who are. When you start discussing the level of marksmanship that requires procedures that MachIVShooter listed you are way past the Sniper level of ammunition selection.

Well said. And, I don't mean to undermine Chris Kyle's legacy but most of his shots were under 200 yards. People that do not know act like its huge accomplishment to ambush and hit a man sized target at 200 yards. Anybody that shoots with any distance consistently knows that hitting man sized targets at 200 yards is really pretty easy. Just because someone can do that doesn't necessarily make them more precise than their neighbor could be. And, if I am not mistaken, in his book, Kyle even states himself that he did not do well initially on some of his first runs with the rifle during training. I could be mistaken on that but it seems like I read that somewhere. Either way, hitting man size targets at 200 yards is not really hard. Now add battle stress into that and its a whole different ballgame. He was very good at what he did and we all appreciate his service but that doesn't make him better than some bench rest guys out there or anyone else at the local range you never heard of.

And, like someone else mentioned shooting is the easiest portion of any sniper training.

 

[tipoc]

A useful post Stumper.

tipoc

 

[200Apples]

.

He was very good at what he did and we all appreciate his service but that doesn't make him better than some bench rest guys out there or anyone else at the local range you never heard of.

And, like someone else mentioned shooting is the easiest portion of any sniper training.

I'd like to remind everyone of what it takes to simply make it through Seals training... but I digress.

 

[Nom de Forum]

.... I don't mean to undermine Chris Kyle's legacy but most of his shots were under 200 yards. People that do not know act like its huge accomplishment to ambush and hit a man sized target at 200 yards. Anybody that shoots with any distance consistently knows that hitting man sized targets at 200 yards is really pretty easy......

When I was at SOTIC one of the range drills was this:

10 shots at a head target

Shooting position was prone supported at 200 meters

The rifle was the M21 with ART-2

At the beginning of the drill a target would not be showing. At random time intervals a head target would be exposed for 2 seconds somewhere along a 10 meter wide area until all 10 targets were exposed during approximately 5 minutes.

You did not have to be one of the best rifle shots in the World to hit all 10 head targets. How do I know this? I was never one of the best rifles shots in the World. Of course this was done with all the comfort of a rifle range and under the stress of training and not with the discomfort of a hide and the stress of combat. There is a reason why Chris Kyle when interviewed for TV said he aimed for the torso. I suspect he made head shots when required and hoped not to many were required. I am no way attempting to demean Chris Kyle.

 

[jerkface11]

Less posting and more reading, my friend.

Maybe you should try less reading and more shooting. The only thing that can keep a cartridge from being accurate is the lack of quality components.

 

[Nom de Forum]

Maybe you should try less reading and more shooting. The only thing that can keep a cartridge from being accurate is the lack of quality components.

:banghead:

 

[d2wing]

A bench rest shooter will tell you that some cartridges are more accurate than others and they work on this all the time. Many cartridges were considered very accurate at one time but have been surpassed by new developments. It is about optimizing. Case design, bullet design, speed, twist rate, powder and other factors. If you make a bullet too long for weight, it will not stabilize, a faster twist rate would help but then you have other problems. If you make it too fat the BC isn't high enough. So it need to be within a range of shapes, and bigger bullets are accurate at greater range.

 

[george burns]

I just used Kyle as an example, I could have used a dozen others , I still think it has more to do with who is doing the shooting, rather than any one type of round being better "in the same class". Some may shoot flatter, faster, of farther than others, but that won't stop the shooter who knows that particular round and it's characteristic. How about Carlos Hancock?
He shot what he had at the time, and did the job with it. I think that has more to do with it than the specific round.
If a kid is brought up with a 30-30 and he shoots that round every day, after 15 years of shooting it, he's going to be pretty good with it, that doesn't mean it's a great round, only that he's great with it.

 

[redneck2]

As noted above, part of what makes some rounds better than others is the shape of the powder column and the total volume of powder to bullet mass. Someone mentioned a .243. I use a .243 for antelope. Most excellent for that. But not for ultimate accuracy. I believe it's too much powder. Not consistent enough. IMO, the more overbore the cartridge and longer the powder column, the more difficult it is to get consistency.

Benchrest shooters don't pick cartridges because of a fad, they pick what they feel are the best ones.

 

[Zaydok Allen]

Great info! Finally, an explanation!

Stumper, that last post, in additions to others from other folks, really helped clear up the pistol side of things in my mind.

 

[cmb3366]

Just going back to the bit about how any cartridge design can dominate a precision oriented sport, the 30-30 case did in fact dominate the short-range benchrest game for over a decade as the 219 Donaldson Wasp, it was the gold-standard that won matches every weekend. Then Merle Walker unleashed the 222 case on the sport and overnight shooters using the 222 in the same actions and barrels used by 219 shooters started winning. The fact of the matter is that the 222 groups more precisely over the long strings measured in benchrest than the 219, and shooters are correct to say that it is inherently more accurate.

At the present date, try shooting a short range match with a 222 built by the finest smith using turned lapua brass and your pet load. You will shoot impressively small groups, but you will be beat when looking at aggregates by the guys running the 6ppc and 30br. Simply put, a mountain of data shows that those two cartridges are capable of putting their bullets in tighter groups than the 222 over the long term, and as a result, they win matches.

All that said, I don't think to the average rifleman needs to be concerned with inherent accuracy. The average rifle, and more importantly, the average barrel just cannot show the difference that exists between cartridges.

 

[natman]

Lots of gobbledygook getting thrown around here. If you build the rifles the same way, load the ammo the same way, and use the same quality of components then it won't matter what cartridge you shoot.

Really? Then why do so many benchrest shooters use the 6mm PPC? According to your theory they could use anything and it wouldn't make a difference, yet in the real world they almost all use an obscure cartridge that's rarely used for anything else. Why don't they use the far more easily available and cheaper 223?

Because the 6mm PPC is inherently more accurate due to it's small size, short powder column and sharp shoulder. You can get almost anything to shoot pretty well, but all else being equal a 6mm PPC will shoot better. The difference may be small, but there are no small advantages in benchrest.