When comparing cartridges, we put way too much emphasis on the cartridge case and nowhere near enough on the projectile.
Table of Contents
Cartridge Case or Projectile?
Part 1 – Which is the Most Important?
In a sort of ‘Chicken or the Egg’ question, when comparing cartridges and buying firearms, which is more important; cartridge case design or projectile construction and design? Too often we read articles about new cartridges that claim amazing ballistic performance, superior to anything that has gone before, and the inference is that it is the specific design of the cartridge case that produces these results. However, is this true?
The truth is that cartridge case design is more about achieving ballistic ‘potential‘ within the physical limitation (size and strength) of available firearm actions. It might also be to capitalize on the attributes of a new firearm design. However, cartridge case design does not guarantee actual ballistic performance because there are many factors that must be balanced to achieve the highest ballistic performance.
These factors include powder weight, powder type, primer, atmospheric conditions, elevation above sea level, barrel length, barrel twist rate, barrel dimensions, chamber dimensions and finally, the projectile. From this list, and without any doubt, the most critical item is the projectile, itself. You can get all of the other parameters right but if you use the wrong bullet then you are not going to achieve the best result.
The Projectile does most of the Work!
It doesn’t matter how good a cartridge case is, whether it is modern or obsolescent, improved or standard, whether it has a conventional or a double-radius venturi shoulder or not. It does not matter if it is belted or non-belted, how much powder the case will hold, or any one of a dozen other attributes. In the final analysis, it is the projectile, and the interaction of the projectile with the barrel, that determines the accuracy and the range of that particular round of ammunition.
Further, if we are talking about hunting ammunition, then it is the projectile, again, that determines the lethality. To state that a particular cartridge is a sure killer, without specifying the projectile in use, is misleading and inaccurate. It is also important to understand the velocity band that our hunting projectile operates within. By velocity band I am talking about the maximum velocity, as the bullet leaves the barrel, and the terminal velocity when the bullet impacts the target. The best hunting bullet in the world will perform poorly if it is operating outside the velocity band for which it was designed.
Sure, case capacity and design are important, but only if we match the appropriate powders to that case and to the bullet weight. However, for cartridges of similar capacities, projectile design is of far greater impact. Let’s face it, when you discuss any particular calibre, there are dozens of cartridges which have similar powder capacities. Just look at some of the most popular calibres, such as 6.5mm, 7mm and .30 calibre, and there are dozens of similar cartridges for each calibre. Despite all of these differing designs, the case capacities are often quite similar and, so, the importance of each of these designs is largely overstated.
Example One
To illustrate what I am talking about, I recently I read an article about the 6.5 Creedmore that claimed “The cartridge (6.5 Creedmore) stays supersonic and maintains its accuracy to past 1,200 yards.” This is, of course, a questionable statement that ignores the fact that it is the projectile that actually does the job that is described in this statement. This statement also assumes, without actually stating it, that you are loading a projectile that is ballistically efficient with a very high ballistic coefficient. This distinction is important because, if you were to load a ballistically inefficient projectile, such as a 160 grain round nose, then it wouldn’t stay supersonic past about 600 yards and accuracy would most likely drop off somewhere about this point. In addition, once past about 300 yards the trajectory of this projectile would be something like a rainbow in shape.
Further, to infer that the 6.5 Creedmore is some sort of wizard cartridge, ahead of the rest of the field, overlooks that fact that there are other 6.5 cartridges that have equal or greater powder capacity. If these cartridges are used with the same barrel dimensions and twist rate and loaded to similar pressures and fed with the same projectiles, then the ballistic results will be pretty much the same. Cartridges that fit these criteria are the .260 Remington, the 6.5×57 and the 6.5×55 Swedish (these last two when chambered in modern rifles). Other cartridges that should match, or exceed, the 6.5 Creedmore’s performance would include the 6.5×284 and 6.5/06. If you are not concerned by short barrel life, then you can also include 6.5 Remington Magnum, .264 Winchester Magnum, 6.5×68 and 6.5/300 Weatherby. The point is that all of these cartridges would produce similar results if using the same barrel, the same projectile and at the same velocities
This is not an attack on the 6.5 Creedmore but it is an attack on the notion that any particular cartridge is superior, to its peers, without taking all of the other ballistic variables into consideration. The old saying, that you must compare apples with apples and not with oranges, is absolutely true when comparing cartridges, too. Unfortunately, many firearms and ammunition manufacturers are only too happy to compare apples with oranges, especially when it results in greater sales.
Example Two
Let’s look at another example. If you visit the website of the ‘King of High Velocity’, Roy Weatherby, we see a similarly misleading view expressed. On the Weatherby Ammunition page, there is the claim that “Nothing Shoots Flatter, Hits Harder or Is More Accurate.” Yet Weatherby do not make projectiles so how can they honestly make this claim? Their cartridges may have the potential to achieve these claims but, without matching their cartridges to the very best projectile for the job, the claims are basically meaningless.
To see what I mean, let us compare the .375 H&H Magnum and the .378 Weatherby Magnum. It is generally accepted, among African professional hunters, that the .378 Weatherby is very often a poorer choice than the old H&H round. The reason is that, until recently, most .375 projectiles were designed to work at H&H velocities. When you push these same projectiles, at the higher velocities of the .378 Weatherby, they tend to over-expand and under-penetrate. To be able to utilize the full potential, of the .378 Weatherby, very careful projectile selection is absolutely essential. This is a clear example which proves that the projectile is far more important than the cartridge that is driving it.
In Part 2, I will look at how we might correct this situation and finally be able to compare cartridges fairly and honestly. See: Part 2 – How to sort out this mess!.
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