Compared: The .243 Winchester, 6mm Creedmoor, and .240 Weatherby Magnum
by Gary Zinn
Anyone who wishes to hunt with a high performance 6mm (.243”) caliber cartridge has only a few options. The firmly established, highly popular .243 Winchester is widely used for hunting both small to medium sized Class 2 game and varmints, and the .240 Weatherby Magnum is there for anyone who wants as much sound and fury as can be packed into a 6mm package. The 6mm Remington (originally .244 Remington) has been around almost as long as has the .243 Winchester, while the .243 Winchester Super Short Magnum came along more recently, but neither of these is a noticeable force in the hunting rifle and ammo market. However, there is a new kid on the block. As I write this in 2019, the 6mm Creedmoor has been in existence for only a decade. The cartridge has become established as a contender in PRS target shooting competitions during that time, but it is only within the last couple of years that production rifle and ammunition makers have begun to offer rifles and ammo clearly aimed at the hunting market. Thus the question arises whether the 6mm Creedmoor may become a significant player on the game hunting scene. If so, the cartridge will have to shoulder its way in with the .243 Winchester and the .240 Weatherby Magnum. Hence this comparison of the three cartridges, featuring strong performing hunting loads for each.
The
Comparisons
The
characteristics compared include maximum point blank range, far
zero and trajectory,
velocity and energy,
sectional density,
killing power, and recoil. Here are the factory loads I will evaluate
and compare. (MV means muzzle velocity, BC means G1 ballistic
coefficient.) .243 Winchester loads Browning 97 grain BRX — MV 3100 fps, BC .370 Federal 100 grain Sierra GameKing (SGK) — MV 2960 fps, BC .430 6mm Creedmoor loads Barnes 95 grain LRX — MV 3150 fps, BC .436 Hornady 103 grain ELDX — MV 3050 fps, BC .512 .240 Weatherby Magnum loads Weatherby 100 grain Norma spitzer (NorS) — MV 3200 fps, BC .302
Weatherby
100 grain Nosler Partition (NosP) — MV 3406 fps, BC .384 +/ 3inch MPBR, Far Zero, Trajectory
I
am a firm believer in sightingin hunting rifles and loads for
maximum point blank range. I feel that a +/ 3inch MPBR is
appropriate for rifles used to hunt Class 2 game, including the
cartridges being evaluated here. My argument is that a prudent and
responsible hunter should never attempt a shot at a game animal
beyond the MPBR of the cartridge/load being used (and closer is
always better). Trajectory matters, because the flatter a bullet flies the easier it is to hit a target down range. Bullet placement is the most important factor in achieving quick, humane kills, so anything that makes hitting easier is desirable.
The
first number for each load is its MPBR yardage, the second is the far
zero yardage associated with the MPBR. Trajectory is noted at 100
and 200 yards, and the
5yard increment
closest to MPBR
(for a rifle sightedin for a +/ 3 inch MPBR, computed for a scope
mounted 1.5 inches over the bore). Results are in descending order
of MPBR. .240 Wea. Mag., 100 grain NosP: 325 / 277 yards
Trajectory:
+2.3” (100), +2.6” (200), 3.0” (325) 6mm Creedmoor, Barnes 95 grain: 307 / 262 yards
Trajectory:
+2.5” (100), +2.4” (200), 2.8” (305) 6mm Creedmoor, Hornady 103 grain: 303 / 258 yards
Trajectory:
+2.5” (100), +2.3” (200), 3.2” (305) .240 Wea. Mag., 100 grain NorS: 297 / 254 yards
Trajectory:
+2.5” (100), +2.3” (200), 2.8” (295) .243 Win., Browning 97 grain BRX: 296 / 253 yards
Trajectory:
+2.5” (100), +2.2” (200), 2.9” (295) .243 Win., Federal 100 grain SGK: 289 / 247 yards Trajectory: +2.6” (100), +2.1” (200), 3.0” (290) One of the prime virtues of these cartridges is that they shoot long and flat. Though the +/ 3” MPBRs of the loads examined here run from 289 to 325 yards, I believe that it is better to limit shots on Class 2 game larger than deer to no greater than the far zero distances of most 6mm loads. This may be heresy to 6mm cartridge fanciers, but I will explain my reasoning in the discussion of killing power, below.
Velocity
and Energy Velocity flattens trajectory and makes hitting easier as the range increases. It is also the most important factor when computing kinetic energy. Energy is a measure of the "work" a bullet can do, which in this case means powering bullet penetration and expansion. Energy is an important component of killing power, as will be discussed below.
To
the best of my knowledge, MVs for these loads are from 24inch
barrels, except the .240 Weatherby MVs are from 26inch barrels.
Here
are the velocity in feetpersecond (fps)
and energy in footpounds (ft. lbs.) figures for our comparison loads
at the muzzle, 100 and 200
yards, and at
the 5yard increment nearest to the +/ 3inch MPBR of each load. The
loads are listed in descending order of MV. .240 Wea. Mag., 100 grain NosP Muzzle  3406 fps / 2576 ft. lbs. 100 yards  3136 fps / 2184 ft. lbs. 200 yards  2883 fps / 1845 ft. lbs.
325
yards  2586 fps / 1485
ft. lbs. .240 Wea. Mag., 100 grain NorS Muzzle  3200 fps / 2274 ft. lbs. 100 yards  2875 fps / 1836 ft. lbs. 200 yards  2574 fps / 1471 ft. lbs.
295
yards  2305 fps / 1180
ft. lbs. 6mm Creedmoor, 95 grain LRX Muzzle  3150 fps / 2093 ft. lbs. 100 yards  2925 fps / 1805 ft. lbs. 200 yards  2712 fps / 1551 ft. lbs. 305 yards  2498 fps / 1317 ft. lbs. .243 Win., 97 grain BRX Muzzle  3100 fps / 2070 ft. lbs. 100 yards  2839 fps / 1736 ft. lbs. 200 yards  2594 fps / 1449 ft. lbs.
295
yards  2372 fps / 1212
ft. lbs. 6mm Creedmoor, 103 grain ELDX Muzzle  3050 fps / 2128 ft. lbs. 100 yards  2862 fps / 1874 ft. lbs. 200 yards  2682 fps / 1646 ft. lbs.
305
yards  2501 fps / 1431
ft. lbs. .243 Win., 100 grain SGK Muzzle  2960 fps / 1946 ft. lbs. 100 yards  2742 fps / 1669 ft. lbs. 200 yards  2534 fps / 1426 ft. lbs. 290 yards  2355 fps / 1232 ft. lbs.
These
results are pretty much as one might expect, based on the MVs of the
various loads. The one noticeable exception to the general downrange
velocity and energy patterns is the .240 Weatherby Mag. load with 100
grain Norma spitzer bullet. Though it has the second highest MV of
the loads evaluated, this load has a MPBR of only 295 yards, and
generates the lowest energy at
MPBR among
the loads listed. Why? Because the bullet has, by a wide margin,
the lowest BC (.302), of the bullets in the various loads. I will
discuss this further below.
Sectional
Density
Sectional
density (SD) is the ratio of a bullet's weight in pounds to the
square of its diameter in inches. SD affects penetration, as all
other factors being equal (bullet construction, for example) the
bullet with the highest sectional density will penetrate deepest.
Obviously, to kill cleanly, any hunting bullet must penetrate into
the animal's vitals, so hunting bullet SD is important. A
bullet SD of .200 has long been
considered about
the minimum acceptable for Class 2 game. Here are the SD numbers for
our comparison bullets, in descending order. 103 grain SD .249 — 6mm Creedmoor load 100 grain SD .242 — .243 Win. and .240 Wea. Mag. loads 97 grain SD .235 — .243 Win. load 95 grain SD .230 — 6mm Creedmoor load There is no important difference in the SD values of these .24 caliber hunting bullets. All are comfortably above the .200 SD benchmark for bullets suitable for hunting Class 2 game, but none have a SD high enough to make them attractive for use on Class 3 animals. (I feel that a 140grain, .277 caliber bullet (SD .261) is a good baseline for effective Class 3 hunting bullets, especially at longer range — say over 200 yards. I mean this not as a hardandfast rule, but as a general guideline.)
Killing
Power
Killing
power is the most difficult factor to estimate, as there is no
definitive scientific formula to apply. Various systems have been
created to estimate the killing power of rifle cartridges, with
varying results in terms of accuracy. Unfortunately, many such
systems have no correlation with reality at all.
One
of the best, in terms of positive correlation with reality, has
proven to be the G&S Online Rifle Cartridge Killing Power
Formula. Not only is it generally consistent with results in the
field, it can be used to compare any load at any range and includes
the factors of energy at impact (which includes velocity), SD and
crosssectional area in an easy to use formula to arrive at a Killing
Power Score (KPS) for a given load at a given distance, via the
formula:
KPS
at "y" yards = (impact energy at y yards) x (sectional
density) x (crosssection area), or simply: KPS
@ y = E @ y x SD x A
(The
crosssection areas of a .243inch diameter bullet is .0464 sq. in.)
Note
that this is a comparative system. We estimate that a rifle cartridge
should generate a KPS of at least 12.5 at the range the bullet
impacts to be a viable hunting cartridge for common Class 2 game, up
to roughly 150 pounds (e.g., deer and pronghorn), while a KPS of 15.0
gives a margin of killing power for larger Class 2 game (up to 300
pounds).
I
calculated the killing power of these loads at 100 yards, as most
whitetail deer, blacktail deer and feral hogs are killed at 100 yards
or less. KPS values at 200 yards and the 5yard increment closest to
each load MPBR are included, to document the power of the loads
further downrange, including near
the longest
range (MPBR) at which a responsible hunter should use them. Loads are
listed in descending order of 100 yard KPS values. .240 Wea. Mag.,100 grain NosP: KPS 24.5 (100 yds.), 20.7 (200 yds.), 16.6 (325 yds.) 6mm Creedmoor, 103 grain ELDX: KPS 21.6 (100 yds.), 18.9 (200 yds.), 16.4 (305 yds.) .240 Wea. Mag., 100 grain NorS: KPS 20.6 (100 yds.), 16.5 (200 yds.), 13.2 (295 yds.) 6mm Creedmoor, 95 grain LRX: KPS 19.3 (100 yds.), 16.6 (200 yds.), 14.1 (305 yds.) .243 Win., 97 grain BRX: KPS 18.9 (100 yds.), 15.8 (200 yds.), 13.2 (295 yds.) .243 Win., 100 grain SGK: KPS 18.7 (100 yds.), 16.0 (200 yds.), 13.8 (290 yds.) All these loads have general Class 2 game power (KPS > 15) at 200 yards, but only the first two carry that much killing power to their MPBR distances. The remaining loads have MPBR power that is adequate for deer and other small to medium sized Class 2 game (KPS > 12.5).
(Our
KPS parameters and results assume vital area hits, of course. A game
animal hit somewhere other than in the vitals is not likely to go
down cleanly, no matter the size, weight and impact energy of the
bullet. This is why I preach the "never take a shot beyond MPBR,
and closer is always better" doctrine. Shorter range shots
improve the likelihood of placing a bullet in the right place.) If I had to choose one of these cartridge/load combinations as an allpurpose tool for hunting Class 2 game, it would be the 6mm Creedmoor, with the Hornady 103 grain ELDX bullet load. To me, this is the best balance of range, power, and modest recoil (see below) among the calibers and loads analyzed. The numbers indicate that this is the highest performing of the few hunting loads currently produced for the 6mm Creedmoor.
I
suggested earlier that shots on Class 2 game larger than deer be
limited to the far zero
distance
of less powerful 6mm loads. Here are the implications of doing so:
The .240 Weatherby Mag. load with 100 grain Norma bullet has a KPS of
14.5 at 255 yards; the 6mm Creedmoor 95 grain load KPS is 15.1 at 260
yards; the 97 grain .243 Winchester load gets a KPS of 14.2 and the
100 grain .243 load a KPS of 14.8, at 255 and 245 yards,
respectively. Keeping it simple, these loads will be most reliable,
in terms of killing power, if shots on Class 2 game are limited to
about 250 yards, since KPS values will be very near to 15 at that
range. What about lighter (e.g., 80 to 90 grain) .243 hunting bullet loads? I have done the math for several .243 Winchester loads with such bullet weights, and the killing power of these begins to fail badly beyond 200 yards. They simply do not carry energy and terminal power downrange as well as 95 grain or heavier bullets. Further, the lower sectional densities of these lighter bullets do not bode well for effective penetration and bullet expansion at longer ranges. The milder of the two .240 Weatherby Mag. loads needs a closer look. I infer that this was intended to be a softer shooting and less expensive alternative to the hot load with the Nosler Partition bullet. Muzzle velocity of the 100 grain Norma spitzer load was reduced 200 fps by using less powder (I presume) and, with the relatively inexpensive bullet, sells for half the price of the “premium” load. However, it suffers from some unfortunate loss of performance. The load has a MV of 3200 fps, with a MPBR of 297 yards. At 295 yards, the bullet velocity is 2305 fps, energy is 1180 ft. lbs., and KPS is 13.2. This is lower long range performance than that of the 100 grain, .243 Winchester load at 290 yards, and is far short of what the stronger .240 Weatherby Mag. load does at 325 yards. Blame the relatively low BC (.302) of the common spitzer bullet used. The only upside to performance is a reduction in recoil to 13.6 ft. lbs., compared with 16 ft. lbs. for the strong .240 load (see below). Just for fun, I concocted a better mild load for the .240. I started by finding a relatively high BC 100 grain bullet with a low price, the Speer #1220 SPBT (BC .430, price about $17 per hundred). Then I consulted the Hornady Handbook of Cartridge Reloading (10th ed.), where I read that 42.3 grains of IMR4064 powder under a 100 grain bullet would get 3100 fps MV in a .240 Weatherby with a 24” barrel. MPBR is 302 yards; energy is 1340 ft. lbs. and KPS is 15.0 at 300 yards. Estimated recoil in an 8 pound rifle is 10.8 ft. lbs. Norma (which makes Weatherby branded ammo) needs my services.
Recoil Besides the specified bullet weights and MVs of our example loads, I used representative powder charges for each cartridge/bullet weight/MV (from reputable load data tables) and an assumed field ready rifle weight of 8 pounds to estimate the recoil energy of each load. .243 Win., 100 grain SGK: 10.2 ft. lbs. 6mm Creedmoor, 95 grain LRX: 10.4 ft. lbs. 6mm Creedmoor, 103 grain ELDX: 10.6 ft. lbs. .243 Win., 97 grain BRX: 10.8 ft. lbs. .240 Wea. Mag., 100 grain NorS: 13.6 ft. lbs.
.240
Wea. Mag.,100 grain NosP:
16.0 ft. lbs. Recoil estimates for the .243 Winchester and 6mm Creedmoor loads fall within a small range, and are very similar to recoil estimates for the .3030 Winchester, firing conventional 150 or 170grain bullet loads in an 8 pound rifle. These are recoil levels that generally will not be daunting for even neophyte, small statured, or recoil sensitive shooters.
Recoil
of the .240 Weatherby Mag. loads is at a different level. The milder
load, with the Norma spitzer bullet, has about the same recoil as an
8 pound .270 Winchester rifle, firing a 110 grain bullet at 3200 fps
(the same MV as this .240 Weatherby load). The stronger .240 load
generates recoil very close to that of an 8 pound .308 Winchester
rifle, firing a 150 grain bullet at 2800 fps. These are not daunting
recoil levels to most experienced shooters, but are clearly more
substantial than the recoil generated by the other two 6mm
cartridges.
Additional
Thoughts and Conclusions
Where
does the 6mm Creedmoor fit in a world where the .243 Winchester and
the .240 Weatherby Magnum are well established in the caliber slot? I
have no definitive answer, just some thoughts on things that may
work in favor of the Creedmoor, others that suggest it may really not
go anywhere as a hunting cartridge.
First,
the 6mm Creedmoor does not dominate the .243 Winchester in
performance, when both are stoked with hunting loads. Though the two
Creedmoor loads evaluated in this article mostly outperformed the two
.243 loads, the differences are small. Certainly such performance
differences are not enough to make hunters abandon their .243
Winchesters en masse and stampede to the 6mm Creedmoor.
(Lest
readers think I am ignoring the .240 Weatherby Magnum at this point,
I will note that it clearly outperforms the .243 Winchester and 6mm
Creedmoor downrange. However, the Weatherby has been around for half
a century and has not achieved preeminence in the 6mm bore slot in
that time, so there is no reason to believe that it will do so in the
future.)
The
intangible that the 6mm Creedmoor has going is that it is the direct
descendent of the highly successful 6.5 Creedmoor. (For anyone who
is unfamiliar, the 6mm Creedmoor case is the 6.5 Creedmoor case
necked down to take .243” bullets, with a couple of
additional very
small case geometry tweaks.) The 6.5 Creedmoor has accomplished
something that no other .26 bore cartridge has ever done, i.e., it
has gained great favor with American shooters and hunters. My point
is that the 6mm Creedmoor may ride to commercial success on the
coattails of its sibling. Name recognition is often a powerful force
in marketing, and the “Creedmoor” label might have
such force. (As an aside, I wonder if Hornady might have a .270 Creedmoor on the drawing board. If so, would it do anything, performance wise, that the 6.5Creedmoor/.260 Remington/6.5x55SE trio or the 7mm08 Remington cannot?) Ultimately, whether the 6mm Creedmoor becomes a notable commercial success may depend on how strongly and persistently Hornady promotes and supports it. I believe that it was sustained promotion and support by Hornady that carried the 6.5 Creedmoor to preeminence in its caliber slot, so the same strategy might work for the 6mm Creedmoor. Notice that I just used the word “might” instead of “will.” My word choice is because the 6mm Creedmoor has a steeper hill to climb than did the 6.5 Creedmoor. Prior to the 6.5 Creedmoor, the .26 bore slot had no preeminent cartridge. The most popular .26 caliber cartridges, the 6.5x55 SE and .260 Remington, both had moderate success in the American rifle and ammo markets, but neither could be called dominant. Thus the 6.5 Creedmoor, though not ballistically superior to those cartridges, had a relatively unimpeded path to prominence. It seems that Hornady recognized this, and sustained its investment in the 6.5 Creedmoor until the cartridge broke through.
The
.24 bore landscape is different. The .243 Winchester dominates, with
a track record and reputation that is daunting for any challenger. The
.243 has a strong support infrastructure in place — i.e.,
rifles chambered for the cartridge and brands and loads of factory
ammo everywhere one looks. Anyone who owns a good .243 Winchester
rifle has little if any incentive to switch to a 6mm Creedmoor,
because there is little performance difference between the
cartridges, and 6mm Creedmoor rifle and factory ammo choices are very
limited (as I write this in 2019). Someone shopping for their first
.24 caliber hunting rifle has many more rifle and ammo options on the
.243 Winchester side than on the 6mm Creedmoor side, so going with a
Creedmoor is an inherently hard sell here, too.
For
those who sweat the details, the 6mm Creedmoor has some subtle
merits. First, the Creedmoor is a highly efficient cartridge,
somewhat more so, on average, than the .243 Winchester and much more
so than the .240 Weatherby Mag. (The difference in efficiency
between cartridge loads can be measured by MV generated per grain of
powder used in the respective loads.
Anyone can do the math, between individual cartridges/loads or for
groupings.) Also, both the 6.5 and 6mm Creedmoor cases are designed to use long, heavyforcaliber bullets within the OAL limits of short (.308 Winchester length) actions; this derives from the Creedmoor case originally being designed for long range target shooting, where heavy bullets reign. This means that bullets weighing over 100 grains will load well in the 6mm Creedmoor. Currently, relevant hunting bullets are the Hornady 103grain ELDX and Berger Hunting 105grain VLDBTHP. These long, slick (high BC) bullets generate long MPBRs and high downrange energy and killing power. (Note that .243” diameter bullets weighing over 100 grains work best in barrels with a fast twist — say 1:9, 1:8, or even slightly faster. Most production rifles chambered in .243 Winchester or.240 Weatherby Mag. have a barrel twist rate of 1:10, which does not stabilize bullets weighing over 100 grains well. This is why .243 and .240 commercial ammo is seldom if ever loaded with bullets weighing over 100 grains, and why heavy bullet reloads in these calibers tend not to be as accurate as lighter bullets. Meanwhile, the few 6mm Creedmoor rifles being produced feature fast twist barrels.)
All
things considered, I doubt that the 6mm Creedmoor will come to
dominate its caliber slot. It may become a significant second fiddle
to the .243 Winchester, or it may fizzle. I simply do not think that
the environment is right for the 6mm version of the Creedmoor
cartridge to duplicate the market success of its 6.5mm counterpart. 


Copyright 2020 by Gary Zinn and Chuck Hawks. All rights reserved.
