.264 Mag bullets "different?"


New member
Aug 22, 2001
Henderson, KY
Newbie question deluxe! In a question/answer article in the latest Shooting Times, Layne Simpson says that the original (c. 1958) .264 Win Mag bullets were .264 at the shank, but was reduced to .257 just forward of the shank. The shank was groove diameter and the body was bore diameter. This "two-diameter" bullet allowed the bullet to be seated forward with "all of its length out of the powder chamber of the cartridge." It also allowed the bullet to be fired at higher velocities than a conventional bullet at the same pressures.

Now, though, the two-diameter design has been dropped from the .264 lineup, and Simpson says that this is "the primary reason why today's handloaders find it impossible to load the .264 Magnum to its original velocity of 3200 fps at acceptable chamber pressures." He goes on to say that factory ammo is also now shorter in length due to the conventional bullet and is considerably slower than the original.

*Whew!* Does anybody have any comments or thoughts on this? Being the relative newbie, I had never heard of a "two diameter bullet," but it sounds reasonable to me. Educate me!
Gib, If you multiply 6.5 times .03937(the conversion factor for metric to inches), you will find out that it comes out to about .257 which is the bore diameter for a 6.5 caliber rifle. The groove diameter which allows for the engraving of the bullet to add spin and thus create stability in .264. That translates into .0035 deep grooves in the barrel which is about standard for most calibers.

The logic behind the two diameter bullet was to reduce resistance be reducing the amount of bearing surface that actually got engraved while providing enough bearing surface to induce the required spin to stabilize the bullet. This is much like a "spin ring" on an artillery round. With the reduced diameter, you had to have more length to maintain the same weight. So...you have longer bullets and less drag and higher velocities, longer COL, etc.
The one thing that that article doesn't mention is the legal interventions that have taken place since 1958.

If some lady had spilled hot coffee in her lap while driving then tried to sue the restaraunt that sold her that coffee because it was not marked "hot", they would have laughed her off of the face of the planet in 1958. Unfortunately, that is no longer true since Justice Cordozza handed down the questionable "deep pockets and implied liability" ruling. I think that was in 1972. Not sure. That was the beginning of the end of logic for our court systems.

Anyway, a couple of things that Mr. Simpson didn't account for in the article are the greater diversity of powders available today and the better made barrels. I believe that 3200 fps is quite easily achieved with the 264 Win Mag, 140 grain bullets, and the right load. My favorite is IMR 7828, Winchester Brass, and Fed 215 primers. I get slightly over 3200 fps for an average velocity. So all in all, Mr. Simpson's article is only partially correct.
I thought I remembered you saying you got decent velocity out of yours. Undoubtedly he's speaking from theory rather than direct experience.

I understand the concept behind the two-diameter bullet; pretty decent idea. I'm not terribly familiar with artillery, so the "spin ring" is (was) foreign to me. Too bad a good thing has to be dumped because of possible litigation by idiots. :(
I think what he is referring to is the reduction in factory ammunition velocity.

A spin ring is a sythetic material ring that is placed around large caliber artillery shells to induce projectile spin and stabilize trajectory. They use this ring because the wieght of the casing and the hardness of some of them would tear up the rifling in the bore. It's a simple idea and works well. It is much the same as the sabot idea, but it doesn't come off. :cool:
I have a question regarding the .257 and .264 cal. cartridges. These two, as are the .277 and .284, are soo close that I was wondering what the real differences are? I understand that the .264 comes in much heavier bullets, but why can't heavier .257 bullets be made? I find it funny that .007 inches really makes all that much difference!! I have read where many people think that the .264 Mag is okay for elk, but something like the .257 Weatherby is too light!! I just need someone to show me the light!! :confused:

BTW- I was over at a friends house to see his trophy room last Friday. He has some of the most impressive mounts that I have saw!! Big elk and a muley that goes 205!! Asked him what gun he uses. Said he has been using the 25.06 for years with 100gr bullets!!! His wife even shot a 50" moose here in UT with that gun earlier this fall.
I read that article by Simpson, most of it is bunk. Layne is trying to sell people on the 7mm STW and .257 STW cartridges. The .264 Win Mag is a direct "competitor" for these two cartridges, sot to speak, so Layne is trying to eliminate some competition here.

I measured some of my .264 bullets, and the Speer Grand Slams are two diameter bullets. Barnes and Noslers are not. As far as velocities are concerned, I have a 24" barrelled Ruger Model 77 MK II, and get 3,140 fps with 140 grain Partitions, and 3,205 fps with Barnes XLC coated bullets. 120 grain XLCs zip along at 3,410 fps.

Don't believe everything (or maybe ANYthing) you read in the gun rags. Everyone has agendas nowadays, and money is driving most of them.

As for the .257 Wby vs. .264 Win Mag, check out the sectional densities and ballistic coefficients of their respective bullets. The 6.5 mm bullets retain more velocity downrange, delivering more terminal energy and driving deeper, hence most folks give them the nod for larger game.
Nodak, Thanks for that. I seldom use Grand Slam bullets, and never in .264. I didn't realize that they are two diameter bullets.

Like you, my 264 Win Mag realized over 3200 fps with 140 grain partitions. I shoot a max load of IMR 7828 and a Fed 215 primer. Average velocity is about 3225 +or-.

I sincerely agree with the agenda comment. Especially when it applies to gun mag writers. Think about it. These guys go on several hunts each year that are sponsored by the different manufacturers, they get to test fire different rifles, they get freebies from the optics companies, and they get to write off all of thier expenses on taxes. Given all of that, wouldn't you tend to be nice to the hand that feeds you? I certainly would.

Specifically, Layne Simpson, in an article about a year ago, claimed that the 6.5 STW was the best of all of them. I had never seen that before, nor have I seen it since. I would agree with his remark. The gun manufacturers on the other hand, produce barrels in 25 and 28 caliber at a much higher rate than they do in 26 caliber. I can understand why they wouldn't want to do a big production shift. IT COSTS MONEY.

As to effectiveness of the 26 caliber vs. the 25, 27 or 28.. I've stated my opinion on that subject several times. I think the 26 has the advanatage on all of them. In bullet weights from 120 grains to 164 grains they will out perform any of the others when taken in relative weight to caliber comparisons.

The biggest thing about all of this is that just about any modern cartridge will work. Hell, Roy Weatherby killed a Cape Buffalo with one shot from a 257 WBY Mag. So..is it a Buffalo caliber??? There have been lots of Elephant and even lion taken with a 6.5 Swede. Would you hunt lion with it?? What can anyone say about the 7mm Mauser round except I wish I had a nickel for every animal it's taken. The key word, as Nodak pointed out, is MONEY. What can we sell? Who can we sell it to? How much can we charge? How do we advertise it? Product, Price, Placement, Promotion. The 4 P's of marketing. It's all about money....

I would have to agree with all of that, but I would have hoped that someone writing for a nationally recognized, supposedly reputable mag would at least be technically accurate. I'm sure he gets a bazillion letters a day; if he can't answer the question truthfully, why bother publishing it? Oh, well...so much for "reliable information." :( Dan, I guess that's why you'll never see a factory 6.5 WSM, either; no Crisco to go with the gas. Maybe they can sell it in Sweden....
Gib, I'm sure that within specific parameters, i.e. factory ammo, selected bullets, specific bullets used in factory ammo, etc., that the article is accurate and technically correct. You also have to remember that these guys write for the general public. I don't think that they realize how many of us are actually into not only reloading, but ballistics and terminal performance as well. (If you think about it, it's really just an extension of reloading anyway.) The more you read, the more anomolies you will find. Eventually, you'll learn which authors are generally correct, which articles have solid information and which ones are presented for general consumption. The latter being the primary focus, probably because they require the least research.

Anyway, it's good that you can pick up on these questions and are willing to ask. It shows that you, unlike those of us that have been doing this for a long time, don't know everything. ;):D :cool:

<FONT COLOR="#800080" SIZE="1">[ November 16, 2001 10:35: Message edited by: danr55 ]</font>
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