An In-Depth Discussion Of The 243 Vs. 308 Calibers

            The .308 Winchester has been a wildly popular round since it’s introduction in 1952. Chambered in sporting handguns and rifles of all types, it even served as the parent case for the similar (but not identical) 7.62 NATO, which has gone on to be used in all manner of military firearms. Suffice it to say, the .308 is here to stay, and it has left a lasting impact on the American shooting public.

Now while one might argue about some sort of mythical “perfect round” there is really no such thing, which is why there are so many different cartridges. However, from time to time there are rounds which are worth comparing to each other, and that is why we are taking a look at the .308 Winchester vs .243 Winchester, which is simply a .308 case necked down to take a .243 bullet. There is some overlap in the functional uses of these rounds, and also many worthwhile questions as to which is best for what situation.

To that end, we will as closely as possible compare the on paper performance of five popular  rounds for each caliber, and let you, the reader make their on decisions as to the merits of each.

History of the Rounds

There is considerable unsourced discussion about the origins of the .308 Winchester, but suffice it to say it was born shortly after the Second World War, when the US Army was searching for a thirty caliber cartridge to replace the aging and somewhat overpowered .30-06 currently in use. 

Work began with .300 Savage cases, and eventually evolved into the .308 Winchester which we know today. Here too, massive amounts of confusion- far more than can be (or should be) covered in an article of this nature occur over the trivial differences between .308 and 7.62 NATO. By 1952 the cartridge was sufficiently developed to justify commercial release. This  new .308 round quickly became popular.

With it’s ability to substitute for the .30-06 in nearly all applications, it didn’t take long for several quality rifles to be chambered for it, and not much longer for shooters to start playing with it.

It is a given if you give enough shooters a cartridge, they will start seeing what can be done to make it better, or what else they can shoot out of it.

One popular method is to neck down the case and shoot a smaller bullet out of it. There are many reasons for this, including higher velocity, to shoot lighter bullets, reduced recoil from lighter/small caliber bullets, and just for the sake of tinkering around.

This sort of thinking soon lead to the creation of the .243 Winchester, which used a 6mm bullet that proved to be flat shooting, and deadly on deer sized game.

Coupled with the volume of the necked down .308 case, it quickly became popular for hunting antelope and similar game where it was difficult to get close to the animal. This created some overlap between uses of the cartridges, which brings us to our comparison.

Comparing the Rounds

It is difficult to compare rounds of identical caliber, let alone of different caliber. There are many factors which affect real world performance, including shooter skill, temperature, barrel length, rifling twist, type of firearm, sights or optics used, even the brand of primer.

To that end, we are going to use published ballistics for five common rounds of each type in a variety of bullet weights, and then consider where the two cartridges exceed, and where there might be little practical difference.

For the purposes of this article, we rely upon data published by Nosler, which has been extensively tested and evaluated under controlled conditions.

It is important to remember that laboratory conditions are not the same as real world conditions, and on paper performance can vary based on temperature, barrel length, rifling twist, atmospheric conditions, and other factors which cannot be readily controlled for.

However, it is a valuable baseline from which to work from and make an informed decision. For each cartridge, we will give the bullet type and weight, barrel length and rifling twist, the powder type and charge, and the velocity at the muzzle. In each case, the round found most accurate by Nosler from their test barrels will be the one listed.

.308 Cartridges Examined

110 grain Varmagedon spitzer, 24” bbl, 1-12” twist, 47 grains Benchmark, 3278 FPS.

125 grain Accubond spitzer, 24” bbl, 1-10” twist, 51.5 grains W748, 3214 FPS.

150 grain Accubond spitzer, 24” bbl, 1-10” twist, 42.5 grains Viht N140, 2887 FPS.

168 grain Ballistic Tip spitzer, 24” bbl, 1-10” twist, 46.5 grains BL-C2, 2698 FPS.

190 grain Accubond spitzer, 24” bbl, 1-12” twist, 36 grains AR-comp, 2256 FPS.

Now as we can see here, the .308 tends to run to heavy bullets, but the lightest bullets which will have the closest overlap with .243 are some pretty zippy rounds.

However, velocity and bullet weight is only part of the overall picture. Done properly, one would chart the ballistic curve of each round and overlay them. Unless you work with real world conditions out of your particular rifle and pet loads, the best you can get is an idea of what a given round plays out on paper under lab conditions.

To that end, suffice it to say, that the .308 tends to not shoot as flat as the .243 over distances.  But first let’s look at the numbers of some .243’s and then start working up some sort of practical comparison.

.243 Cartridges Examined

55 grain Ballistic Tip spitzer, 24” bbl, 1-10” twist, 52.5 grains H414, 3982 FPS

70 grain Ballistic Tip spitzer, 24” bbl, 1-10” twist, 41 grains Varget, 3546 FPS

80 grain Ballistic Tip spitzer, 24” bbl, 1-10” twist, 41 grains RL15, 3354 FPS

100 Grain Partition spitzer, 24” bbl, 1-10” twist, 40 grains RL17, 3033 FPS

105 Grain Custom Competition hollowpoint boattail, 24” bbl, 1-8” twist, 43.5 grains H4831, 2899 FPS

Clearly the .243 operates in the realm of lightweight bullets, which limits the practical utility on game larger than deer. In fact we don’t even get a real overlap between the two cartridges, save around the 105 grain .243/ 110 grain .308, and there we see the .308 is a real winner in terms of speed, by about 400 feet per second. But we’ll come back to those two rounds in a moment.

Uses for Each Round

It is important to remember that the .308 was designed first as a military cartridge, and a replacement for the venerable, and high powered .30-06 Springfield, and that the .243 was designed to shoot a smaller, lighter bullet for hunting deer sized game, varmints and such.

The .308 will always have the edge for heavier bullets and an ability to take larger sized game animals. It is also a better long range target round, although invariably you will find people who will debate pretty much everything I just said here.

The primary overlap between the uses of the two cartridges is hunting deer sized game, although when dealing with the smaller and lighter .243 bullets, shot placement and bullet type selection is extremely important.

Having said that, I would argue, all things being equal, the .243 is the superior deer cartridge, simply due to it’s greatly reduced recoil, but it will require a bit more skill and choice in shot placement than a .308 will.

The .243 also wins hands down for hunting smaller animals such as coyotes, and other varmints and small predators. As can be seen, there are bullets as light as 55 grains available for the .243, which makes it ideal even for prairie dogs, and the greater case capacity of the .243 gives it a powerful edge over other popular varmint rounds like the .223. Using .308, even with lighter weight bullets on anything smaller than coyote is simply overkill.

The .308 shines at exactly where the .243 stops being useful- namely game larger than deer size,  and shooting heavy bullets. However, with greater power comes greater recoil, and the .308 can quickly become uncomfortable for some shooters.

The .308 will reliably take all but the largest and most dangerous North American big game, and also is well suited for certain tactical and defensive roles. A great many police and military sniper and designated marksman rifles are chambered in .308 (or 7.62 NATO), and many private citizens own similar tactical rifles for home or ranch defense.

In fact, .308 AR style rifles are becoming increasingly popular, and here the .308 takes on a unique life of it’s own, inasmuch as the same rifle can readily serve as a tactical rifle, a hunting rifle, and a target rifle, often without even changing the optic. This is a flexibility not readily available in .243 rifles.

One great advantage the .243 has over the .308 is that it has a flatter ballistic trajectory in a similar bullet weight. The smaller diameter bullet shoots flatter over a longer distance, which is especially appealing when shooting offhand. Pulling up a good ballistic calculator, and inputting the information unique to your rifle, load and shooting conditions will quickly let you see just how much flatter a .243 is going to be compared to the .308.

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