I found this article by Chuck Hawks which clears up Winchesters hype on their new 243 WSSM cartridge. Chuck correctly states that Winchester is mis leading the public, and they should have compared their new 243 WSSM to the 6 mm Remington, for which the 243 WSSM more closely performs to.

Compared: The .243 WSSM and .240 Weatherby Magnum

By Chuck Hawks



This article is really Winchesters fault, for having the temerity to compare their .243 WSSM to the larger .240 Weatherby in their advertising and promotional material for the .243 WSSM. Winchester, you asked for it so here it is.



The .240 Weatherby Magnum was introduced in 1968 on a unique belted case with about the same capacity, length, and .473" rim diameter as the .30-06 Springfield. It has, since its inception, been the most powerful of all factory loaded 6mm cartridges. Only the European 6x62 Freres even comes close.



Weatherby offers five different factory loads for their .240 Magnum. These drive an 87 grain Hornady Spire Point bullet at a muzzle velocity (MV) of 3523 fps and muzzle energy (ME) of 2397 ft. lbs., a 90 grain Barnes X-Bullet at a MV of 3500 fps and ME of 2448 ft. lbs., a 95 grain Nosler Ballistic Tip at a MV of 3420 fps and ME of 2467 ft. lbs., a 100 grain Hornady Interlock at a MV of 3406 fps and ME of 2576 ft. lbs., and a 100 grain Nosler Partition also at a MV of 3406 fps and ME of 2576 ft. lbs. The 87 grain Hornady Spire Point bullet is a combination varmint and medium game bullet, all of the other bullets are intended primarily for big game hunting.



The .240 would seem well suited for hunting javelina, antelope, deer, sheep, goats, feral pigs, black bear, and caribou. The 100 grain Nosler Partition bullet is probably the best alternative for the largest game, up to about 400 pounds, that one might reasonably hunt with Weatherby's .240 Mag.



Weatherby offers the .240 Magnum in several of their Mark V rifle models, including the SBGM, Ultra-Lightweight, Accumark, Fibermark, Fibermark Satinless, Stainless, Synthetic, Sporter, and their flagship Mark V Deluxe. All Weatherby .240 rifles are supplied with 24" barrels as of this writing, although they used to be offered with 26" barrels. Weatherby considers their powerful .240 Magnum a big game cartridge and does not offer it in their Super VarmintMaster models.



Winchester introduced the .243 WSSM 35 years later. They offer a Supreme varmint load that drives a 55 grain Nosler Ballistic Silvertip bullet at a MV of 4060 fps and ME of 2013 ft. lbs. That is the highest velocity factory load I can remember since the introduction of the .17 Remington in 1971. Only the .220 Swift, introduced in 1935, claims a higher MV (48-50 grain bullets at 4110 fps).



As shooters discovered back in the 1930's with the Swift, ultra-fast velocity also means ultra-fast barrel wear. It is hard to see the point of this load, as its very stubby bullet will lose velocity faster and drift more in the wind than the common 55 grain .22 caliber varmint bullets. Experience has shown that bullets weighing 70-87 grains are about right for shooting varmints with a 6mm cartridge, but no such load is offered for the .243 WSSM at this time.



Winchester offers two loads for the .243 WSSM intended for big game hunting. One of these is a Supreme 95 grain Ballistic Silvertip bullet at a MV of 3250 fps and ME of 2258 ft. lbs. This is a moly coated version of the same Nosler Ballistic Tip bullet that Weatherby uses in one of their .240 Magnum factory loads. This should be a good bullet at .243 WSSM velocities for javelina, pronghorn antelope, feral goats, and small to medium size deer.



The other .243 WSSM factory offering is a Super-X load using a 100 grain Power Point bullet at a MV of 3110 fps and ME of 2147 ft. lbs. This may be the best .243 WSSM load for North American feral pigs, mule deer, sheep, mountain goats, black bear, and other game than might weigh up to about 300 pounds.



Browning and Winchester make special super short actions for the WSSM series of cartridges. Big game and varmint style rifles are offered. The varmint models come with 24" barrels; the sporter versions of the Browning A-Bolt II come with 21" barrels and the sporter versions of the Model 70 come with a 22" barrels. Winchester .243 WSSM sporter models are the Featherweight and Black Shadow; the Coyote is the varmint model. Browning WSSM versions of the A-Bolt II are the Medallion, Composite, and Stainless sporter models, plus their Varmint rifle.



Both the .243 WSSM and .240 Wby. Mag. are at their best with bullets weighing between 70 and 105 grains, although other weights are offered. Both cartridges use the same 6mm/.243" diameter bullets.



Loaded to the maximum permissible pressure the .240 Weatherby shoots flatter with the same weight bullet than the .243 WSSM because it has significantly greater powder capacity and also operates at slightly higher pressure (53,500 cup compared to 52,000 cup). For example, comparing 95 grain factory loads using Nosler plastic tipped bullets in both calibers, we can see on the "Rifle Trajectory Table" that the .240 bullet has a maximum point blank range (+/- 3") of 327 yards, compared to a MPBR of 312 yards for the .243 WSSM.



With identical 100 grain bullets and full power loads the "Rifle Trajectory Table" shows that the .240 Weatherby has a MPBR of 322 yards, compared to only 296 yards for the .243 WSSM. Figuring the maximum point blank range shows the optimum trajectories for both cartridges. Using a 200 yard zero for both cartridges and calculating the drop at longer range (as Winchester does) would simply magnify the difference between the two cartridges, making the .240 look even better.



So how about the misleading Winchester comparison showing the .243 WSSM to have slightly less drop than the .240 Weatherby? How did they do that? Simple, Winchester's graphs are comparing a reduced pressure .240 load at a MV of 3200 fps to their full power .243 WSSM factory load at a MV of 3250 fps. Naturally, if you under-load the .240 to a velocity 50 fps below that of the .243 WSSM, the latter will have a slightly flatter trajectory. It's a completely bogus comparison, of course.



This takes misleading advertising in the gun world to stratospheric heights. All that it really proves is the old adage that figures can lie and liars can figure. Given bullets of identical ballistic coefficient (BC), higher velocity always makes for a flatter trajectory.



Here is how that Winchester table would look if they showed full power factory loads (Weatherby and Winchester respectively) for both cartridges using the 95 grain Nosler bullets (BC .379) zeroed at 200 yards.



.240 Wby. Mag. (MV 3420 fps): -5.1" at 300 yards, -15.1" at 400 yards, -31.0" at 500 yards.



.243 WSSM (MV 3250 fps): -5.8" at 300 yards, -17.0" at 400 yards, -34.9" at 500 yards.



Due to its higher velocity with identical bullets the .240 Weatherby Magnum generates higher energy at all ranges. Again using the 95 grain factory loads as an example, the energy figures in foot-pounds look like this:
.240 Weatherby Mag (MV 3420 fps, ME 2467 ft. lbs.): 2087 at 100 yards, 1759 at 200 yards, 1475 at 300 yards, 1229 at 400 yards.



.243 WSSM (MV 3250 fps, ME 2258 ft. lbs.): 1898 at 100 yards, 1610 at 200 yards, 1359 at 300 yards, 1140 at 400 yards.



These figures are taken from the published ballistics of the respective factory loads. The .243 WSSM ballistics were achieved in 24" test barrels, while the .240 Weatherby ballistics were achieved in 26" test barrels. The average big game hunting rifle will have a barrel 2" shorter than the test barrel in either case (3" shorter for the Browning .243 WSSM big game rifles). Subtract 100 fps from the claimed MV of both cartridges to get an approximation of the actual velocity in the shorter barrels supplied by the rifle manufacturers. The point to remember is that the relative relationship between the performance of the two cartridges will remain the same. In terms of performance, no matter what you look at (velocity, energy, or trajectory), the .240 Weatherby Magnum is clearly superior to the .243 WSSM. Since the .240 has greater case capacity and has a slightly higher maximum average pressure limit, it can be no other way. It is literally impossible for the .243 WSSM to equal the performance of the .240 Weatherby Magnum with full power loads, whether factory loads or reloads. To put the .243 WSSM's ballistics in proper perspective, let's compare all of the reasonably well known 6mm calibers using full power loads with 100 grain bullets (the most popular weight for big game hunting). The list would look something like this (chronographed in hunting rifles with 24" barrels): 1. .240 Weatherby Magnum - 3350 fps.
2. 6x62 Freres - 3300 fps
3 & 4. 6mm-06 wildcat and 6mm-284 wildcat (tie) - 3200 fps.
5 & 6. .243 WSSM and 6mm Remington (tie) - 3100 fps.
7. .243 Winchester - 3000 fps.
8. 6mm BR Remington - 2650 fps.



One thing this list reveals is that a reasonable comparison would be between the 6mm Remington and the .243 WSSM. But instead Winchester chose to compare their new super short "magnum" cartridge to the .240 Weatherby Magnum.



Next, let's take a look at the .243 WSSM and .240 Weatherby Magnum in terms of killing power. According to the "Maximum Optimal Ranges for Big Game" table, using 100 grain bullets at factory load velocities the maximum optimal range on 200 pound game is: 295 yards for the .243 WSSM, and 400 yards for the .240 Weatherby Magnum. With the same factory loads the maximum optimal range on 400 pound game is: 40 yards for the .243 WSSM, and 150 yards for the .240 Weatherby Magnum.



Being the less powerful cartridge, the .243 WSSM generates less recoil in rifles of equal weight. Using the "Rifle Recoil Table" we can compare 7.5 pound rifles shooting 95 grain bullets at claimed factory load velocities in both calibers. It shows a preliminary figure of 10.6 ft. lbs. of free recoil energy for the .243 WSSM (MV 3250 fps), compared to 12.2 ft. lbs. of recoil for the .240 Wby. Mag. (MV 3420 fps).



Note that while 7.5 pounds is probably a reasonable compromise comparison weight for these rifles, a .243 WSSM rifle with a catalog weight of 6 pounds will actually weigh around 7 pounds after it is scoped, while the average 6.75 pound .240 Weatherby rifle probably weighs about 7.75 pounds with a scope. This difference in rifle weight will increase the actual recoil energy of the .243 WSSM and decrease the actual recoil energy of the .240 Weatherby.



The design of the two cartridges should be touched on briefly as it relates to use in hunting rifles. The .240 Weatherby is a normally proportioned, modern hunting cartridge of proven feed reliability in bolt action rifles. On the other hand the extremely short, extremely fat, sharp shouldered, rebated rim .243 WSSM is a nightmare shape in terms of feed reliability. It looks like a jumbo size bench rest cartridge of the 6mm PPC type, which is intended for use only in single shot rifles. And, in fact, that is the design inspiration for the WSSM cartridges.



It also touches on the reason Winchester built special "controlled round push feed" actions for the WSSM calibers instead of using a shortened version of their standard push feed Model 70. For those who are interested, I go into the subject of reliability in more detail in the article "Bolt Action Rifles for Dangerous Game" on the Rifle Cartridge Page.



Among the major rifle manufacturers, Browning and Winchester chamber rifles for the .243 WSSM cartridge. Only Weatherby chambers for the .240 Weatherby Magnum. So a new .243 WSSM rifle should be easier to find than a new .240 Weatherby rifle. Of course, the .240 has been around for a lot longer, and so have Weatherby rifles so chambered, so .240 rifles are more available on the used market.



Both cartridges are available in ultra-light and light weight rifles. The sporter versions of the Browning and Winchester WSSM rifles weigh about 6 pounds. The Weatherby Ultra-Lightweight rifle weighs only 5.75 pounds in .240 Wby. Mag., even though it is supplied with a 24" barrel. The Weatherby Deluxe weighs 6.75 pounds.



I would summarize the .243 WSSM vs. .240 Weatherby Magnum comparison thusly: the .240 is superior in every performance category, period. The performance of the .243 WSSM is actually nearly identical to that of the 6mm Remington cartridge, while the .240 Weatherby is a true magnum cartridge. So if you are looking for magnum performance, the .240 Weatherby is the obvious choice.



If you prefer the Browning A-Bolt II or Winchester Model 70 rifles you will have to settle for the .243 WSSM, as neither chambers for the .240 Weatherby Magnum. If you prefer the Weatherby Mark V rifle, you will have to get the .240, as Weatherby does not chamber for the .243 WSSM.

Back to the Rifle Information Page

You can find Chuck Hawk's excellent cartridge articles online by searching for his name. He is an excellent author regarding cartridges!

Copyright 2003 by Chuck Hawks. All rights reserved.

Chuck is wrong on most of his points. But it's free just like this site.

He has not even seen a 243 WSSM as far as I can tell. When the cartridge gets finalized then a valid comment can be made.

Right now the best 6mm cartridges are the 6mm Rem and the 6mm PPC for bench shooting.

Somthing else to consider is a barrel is measured from the muzzle to the base of the case and so the WSSM's will gain at least a inch of effective barrel length over the 240 Weathery because of the shorter OAL....could be as much as 50 fps and it's "free".

Another couple of comparisons worth doing...243 WSSM vs 6mm AI vs 6mm-284. There was an article in Precision Shooting awhile back on 6mm AI, and the perpetrators were getting nearly the level of velocity from the 6mm AI as the 6mm-284.

Since I already have the 6mm-284, I'm not so tempted by 243WSSM, but wonder a little bit about 243 AI.

Tom

The barrel differences that DB Bill points out are relevant. As us mere mortal handloaders don't have access to whatever "super secret squirrel recipe" powder the factories are using for these new magnums (and the light magnums, as well) we are stuck with what powders we can buy, another relevant point. Given that consideration, it's all about boiler room. The bigger the boiler, the more powerful the locomotive. At least until you can't burn all the fuel anyway. Comparing the new super short magnums to the old medium length standards (for want of a better phrase) is simply advertising hype at it's finest. - Dan

I just got some second hand reports from the boys at Winchester, and they indicate they have gotten as much as 4500 fps with 55 gr ballistic tips from the latest configuration of the 243WSSM. I imagine that is not a lawyer proof load, but, by golly, some of that WBY fodder isn't lawyer proof either.

It's far to early to condemn or praise the 243 WSSM. JMO, Dutch.

When is it going to be out Dutch? The 243WSSM I mean.

I don't know. I just bought some 223WSSM once fired brass that was used in the final testing of Browning factory rifles. Redding is supposed to release the dies next week.

OLIN/USRAC are not at that point with the 243 yet: they are still messing with the barrels. This is second hand information, but they are concerned with barrel life (2,000 rounds), and are trying some things to see if they can extend it, including chrome lining. If I had to pick a date, I'd say late summer at the earliest, but I would not be surprised if we missed hunting season this year.

The good news is that they were shooting groups as small as .25" with some configurations. FWIW, Dutch.

Well, they probably picked the 240 WBY figuring that it's an unknown cartridge compared to the more popular 6mm's or the 7mm wby, or 300 wby. People see that the 243wssm beats "a weatherby" then they have to have one.
Sort of like the folks that claim their super-duper 30-06 loads equal the 300 win mags loads.
Obviously if the 300 has a 22 inch barrel, and is severely undercharged, the 06 will "outperform it".
Trigger

just thinking outloud here. i understand the vermin factor of the wssm but if you are firing a 75 plus grain pill why not shoot a 25-06 or an 25-06ai and just be done with it? seems like the 270 280 debate. plus the guns are cheaper[read used] and factory amo is everywhere. am i missing something?
the 22 offering doesn't really fly up the skirt either but that one i can almost see.
just mumbling
thanks
woofer

Woofer although i want one of the wssm, i have often thought about the same thing

I ordered my M70 Coyote in .223 WSSM last Dec. and so far it's not here yet. Just went by the store and no luck. Winchester has stated that the .223 WSSM are being shipped as we speak but that delivery on the .243 WSSM is not slated until late July or August. Isn't it great how Chuck Hawks can write an article on cartridges that he has never fired. He was not in the group of writers that Winchester invited to demo their new offerings so I wonder where he gets his information? Seeing that I already own a .240 Wby. Mark V Deluxe I see no reason to get a .243 WSSM but my granddaughter wants grandpa to build her one. "Why?" I asked her. "Because it's cute" was her reply. Not sound reasoning but as good as Chuck Hawks can come up with. Lawdog

Woofer, what you say makes perfectly good sense. In fact, I would argue that a 25 cal WSSM should have had priority for Winchester because they already have, afterall, the 243 Win. They dont have anything in 25 cal. But then, maybe they see it as improving (or need to improve) their current cartridge offerings.

I agree that a 257 or 264 WSSM caliber would be a dream deer rifle that could also do a lot of good as a varminter. Think I need to build the kids one, each..... LOL! Dutch.

I HAVE GOT A BOX OF .257 75 GRAIN X BULLETS

I think a .257 wssm would be more usefull than a .243, but with the short, fat case, wouldn't the bigger bullet make it front heavy, and prone to feeding problems? It would be like a benchrest cartridge.

what if you just loaded down the wsm and necked to 25? no fancy actions or anything. just a 28" tube in a #4 or #5. that would be a fun one...
woofer

a 25 cal with a 28" barrel? That would kind of upset the idea of a "short light" rifle, wouldn't it?

The 25 WSM would be pushing a lot of powder through a itty-bitty pipe. Downloaded, it would be a good cartridge, but still much more than 95.7% of the deer hunters out there need. JMO, Dutch.

There may not be a "best" full capacity 6mm cartridge yet. The 243 Win has a very short neck and some say rifles blow up with that cartridge but they offer no reasons. The 6mm Rem is pretty good but could have less body taper, more capacity and be a little shorter for some actions. The 240 Weatherby is a Weatherby.

New cartridges are a source of increased sales for the gun and ammo companies. Besides we don't want to say we want fewer new things for rifles do we?

I am not sure if the 243 WSSM will solve any of the above small complaints. But as we read to date it may have a capacity greater than the 308 Win and therefore may be usefull necked up.

As to the 223 WSSM the existing .224 large cartridges have been left behind by their 1-14 twists which are no longer in fashion. Perhaps the 223 WSSM will have a quicker twist so it can use 75 to 80 gr bullets.

A 243 WSSM might make a good long range varmint rifle if it had a fast enough twist. I would have to see it first.

Savage99, if Redding ships their dies next week, like they said they would, I'll tell you how a 9 twist 223WSSM does the next day......LOL!

The internal ballistics programs promise that I can run 75 gr. Amaxes at 3300, and not run pressures much over 50,000 cup. That's one heck of a long range combination. It soundly beats the 6.5/284 to almost 700 yards.

I know they changed the twist for the 223 after they printed the catalog, and they now list it as a 1/10. At WSSM speeds that should be enough to stabilize the 69 gr SMK. FWIW, Dutch.

DUTCH, WHAT DID YOU HAVE BUILT? AND I CAN'T WAIT TO SEE WHAT A 243 WSSM WILL PUSH AN 85 GR PARTITION AT WHEN THEY GET THERE FINAL CASE DIMENSIONS, AS FOR THE 223 WSSM I HOPE TO KILL 5 OR SIX DOES WITH ONE THIS YEAR

Fats, I turned a Savage 11 300 WSM into a switch barrel rig 300/223WSSM. Now that it is done, I'll probably leave the WSSM barrel on it. Used a Pac-nor 3 groove 9 twist 24" stainless barrel, 15moa Farrel Base, 6x24 Sightron, SSS trigger, bedded in Devcon Aluminum.

Did most of the work myself; it was a good learning project. The brass should be here today, and I'll start playing with the magazine block. Since Savage uses their CRF "Safari" action for the WSM's, feeding is not a big concern, but the mag will need to be blocked to ensure proper functioning. FWIW, Dutch.

If the Montana SA's work out for me I may order their WSSM version and make a long range varmint rifle on one in .243 WSSM. Maybe just a sporter weight 26" barrel with a 1-10 twist.

Unless of course someone proves that 107 VLD's will expand at long range.

I'm going to say it. You know, I'm not against cartridge development but hey, how many new cartridges are we going to adopt because of a tenth here or a few thousandths there. A little shorter, a little fatter, a belt here, no belt there and so forth. If you really look at the history of this thing the short magnums are really nothing new at all. The middle-aged .243 is one if you do the numbers and look close. The .300 Savage is only about 3 grains of powder behind the .308 Winchester and only old guns with weaker actions has really limited this one to what it is today. Look at the .350 Remington Magnum and the over-bore beltless 25-06. The more things change - the more they remain the same. Remingtons 'new' Ultra Magnums are nothing but blown-out cases with a lot more room for powder and that's it.

Sizzlebird I am with you on a lot of what you said-"it's the sizzle baby" wasn't that what they used to say in marketing!?

I am waiting to see how the WSSM's work out-me thinks they are gonna have feeding problems. 2000 rounds yeah that is what I would expect-personally I think they are trying to figure out feeding issues not tube life!

"GET TO THE HILL"

Dog

I just read the other day that they've decided to chrome line the barrels of the .243WSSM's.
That scares hell out of me. Barrel life must be pitiful. They aren't chrome lining those barrels for nothing. It has to be for heat dissipation. I'm putting my wallet away for a while. If it turns out to be a winner I'll buy it. If not I haven't lost anything. Best wishes.

Cal - Montreal

Lawdog, and Dutch, I am a happy camper. Lawdog, your suggested load of Imr4831, at 52.2 gr, with a Nosler 100 grain partition is shooting very well in my custom 240 wby. Very good accuracy and groups. I can easily cover 3 shots with a nickel. That still was with me not totally rock solid. I think that's my key deer round, pig round, etc, when I use the 240. Thanks for the load data Gary (Lawdog).

I forgot to mention, if I discounted the first two shots, I only took one fowling shot, then shot a 3 shot group, but the last two shots were inside each other, tells me I may need two fowling shots. At any case, the load is very accurate. I may also try RL 25, or RL 22 in this cartridge.

Got the new Hornady manual this week, and according to Hornady, who put a couple of rifles together based on preliminary published specs, the .223 WSSM showed SIGNIFICANT (their word) barrel erosion after 350 rounds. Yikes!!!
That just doesn't rock my world. The Big Red W can keep these two, I doubt that 4600fps from a 40 V-Max is worth it. They seemed impressed only by how fast it ate barrel throats. I was impressed by 3500 fps with 75 A-Maxes, though, and it is something to think about, for those who can afford a fixed headspace quick barrel change setup like the M-60. I don't think I need one, but I wish them well, and of course, the guys who rebarrel rifles for a living!

one other thing to point out re: problems with CRF feed of Short/Fat cartridges:

CRF is not particularly needed when you're shooting at something that isn't going to bite you back. Cape Buffalo whitetail are not.

A recent article in Rifle points this out re: Browning A-bolts actions with WSM cartridges - push feeds feed these short/fat cartridges just fine (according to John Barsness, anyway)

Troy