Home Forums Hunting & Shooting Ask The Gunwriters .264 WM vs 7mm Rem Mag

Maybe this has been addressed here and I've missed it, but I have a question regarding obtainable velocities using 140 gr. bullets in these two cartridges.

From my research, it seems that SAAMI max pressure for the 264 is 64,000 psi and for the 7mm the max is 61,000 psi.

I was also under the impression (maybe I'm wrong here?) that the cases for these two are very similar. I believe MD even wrote in one of his articles on the 264 that he used some 7mm mag brass he had and resized them to use in the 264, so I can't think that the case capacity between the two is significant.

Therefore, my question: Why do in all of the reloading manuals I have and what I can find from the bullet and powder manufacturers online all say that maximum obtainable velocities for the 264 fall below those for the 7mm?

I've got an older Nosler manual (maybe 6-8 years old now) and Brian Pearce wrote the intro to the 264 mag section. In the intro, he says that obtaining 3200 fps is doable with a 140 gr. bullet. But then the load data shows max. velocity of only around 3000 fps and most powders listed are lucky to get to 2900. Why is this?

In other words, how come I can't get equal velocity in the 264 that I can get with the 7mm?

By the way, I own rifles and load for both of these cartridges, but just kind of realized this last night as I was loading for the 264.

General principle: same size case, same weight bullet, then the bigger bore produces higher velocity

Just physics. Larger bullet has greater total base area, more net force at same psi. More net force, more kinetic energy to push it faster.

DF

Not many loads will get 3200 fps in the 264 that Winchester originally optimistically claimed. People believed it and kept adding powder until they got there but who knows at what pressure? Due to the pressure difference the 264 can come close to the 7RM or within 75 - 100 fps. I can't get more than 3,175 fps with 140s in the 7RM with book loads so what little difference there is the 6.5 will catch up to due to a better BC within 400 yds. or so.

I'm surprised somebody hasn't chimed in before with MD's formula. My mental math says the difference in bore area should account for about 3-4% difference in velocity in favor of the 7mm vs the .264. That's about 90-120 fps and seems about right.

I just never could get myself to buy a 264 Win Mag because I think the 7mag is a little better.I can get 3200fps with a 150gr Ballistic Tip,my favorite bullet for deer and 3100fps with a 160gr Accubond,another great bullet.Brass is easier to find,great selection of bullets in the 7mm and if you buy shelf ammo,prices for that is cheaper too.I have four 7mags,all are great shooters and they all will shoot the same load very well.

There's SAAMI pressure and then there's Campfire pressure...

DF

I would agree that the 7 is "better" for game larger than deer. But one doesn't really need 140grains of bullet for deer. I love my 264 with 125 Partitions or 130ABs at or just under 3300 fps. Pleasant to shoot and very flat.

But then we are picking nits, as per usual...

Well I got 3220fps with 65.0grs of Accurate 4350 and also 70.0grs of Reloader-26 with a 150gr Nosler Ballistic Tip.I don't pay too much attention to book loads with the 7mag.They usually run about 58,000psi.They loaded it way down when they brought out the 7STW.They did the same thing to the 7STW when they brought out the 7mm Ultra Mag and then along came the short magnums which were loaded around 63-65,000psi.I saw a lot of factory short mag stuff that definitely had visual signs of very high pressure.Those short mags had a lot of variation.Some had freebore and some didn't,that's probably why the high pressure signs on factory stuff in those rifles.It just shows you once again,every rifle is different and should be treated as such.

Interesting take on the 7mm mag ballistic history.

^^^This^^^

I prefer my 264 Win Mag with 125 Partitions. Maybe a little less recoil and a little flatter shooting too. I’ve killed a ton of game with that combo over the years and have been EXTREMELY happy with the results.
And I seriously doubt a Mule Deer or an Elk would ever know the difference between a 125 gr or a 140 gr bullet. 🤠

That being said, if I could only have one rifle for medium sized game animals, a 7mm mag with a 140 gr Partition would be my first choice. And I’d also load it with 160 gr Partitions for big game and never look back either. JMHO, though. For whatever it’s worth.

OK. Thanks for the info. Now I know.

Anyone used RL25 or H1000 for 140s in the 264? What velocities were you getting with those powders? Unfortunately, I haven't bee able to snag any RL26 anywhere, so I don't have that to try.

Always wanted a 264. I’ve had several 7mm Remington’s. Settled on a 270 wby which is my favorite . More better I think.
That applies to the 150 and lower weights. Hasbeen

Here is a pair of junkie old 264’s. I think a 270 Weatherby is a bit better also.

baldhunter,

Sorry, but you don't understand what happened with 7mm Remington Magnum pressures and velocities. The change happened a LONG time before the 7mm STW appeared.

When the 7mm Remington was introduced in 1962, the SAAMI industry standards were copper-crusher pressures (then called PSI--pounds per square inch) even though they were worked up with copper-crusher testing, and 26" barrels. As electronic testing started to be used, it was not only determined that copper-crusher numbers were NOT PSI, but the 7mm RM often resulted in wide variations in pressures (both up and down) with certain powder/bullet combinations.

As a result, the SAAMI pressure standards were reduced to accommodate the variations. At the same time, the standard test barrel length for bolt-action cartridges became 24", not 26". BOTH reasons are why the advertised velocities of 7mm RM muzzle velocities were reduced considerably. It had nothing to do with the 7mm STW, which was introduced a long time after those changes.

The 7mm STW's factory ballistics have never been reduced, because they were developed AFTER the change to electronic testting. But you may be remembering when the 7mm was a wildcat, and many people (Including Layne Simpson) were reporting muzzle velocities close to 3700 fps with 140's and 3500 with 160's. But when Remington pressure-tested those loads, they were way over the long-time SAAMI maximum of 65,000 PSI for ANY cartridge. In fact most were 70,000-75,000 PSI. Whether that is a safe pressure level is another question--but SAAMi prefers to stay on the safe side, so the factory-standard velocities were reduced.

I have no idea where you got the idea that 7mm STW factory velocities were reduced because of the 7mm RUM. I checked the record of 7mm STW factory velocities and found they're basically the same as when the round was introduced, though they can be a little lower due to some bullets resulting in higher pressures than others--and some newer bullets do.

The .270 Wby doesn’t get mentioned all that much, but it is a very wicked killer of all manner of game and probably my favorite elk cartridge.

Use 130s, 140s or 150s. The elk don’t seem to notice a difference.

Surprisingly pleasant to shoot, as well.

Hey JOC said his 270 would do anything a 264 would with less powder and noise. LOL


Mike

In his day, he was right. The original .264 ammo did not feature bullets that had ballistic coefficients significantly better than .270 bullets, and muzzle velocities weren't much better in the same barrel lengths.

If I remember correctly he also said he could never detect a diffence in effectiveness between the .270 and 7mm Rem. mag..

Mule Deer I cannot say I totally disagree with what you are saying but when the 7STW was first introduced as a factory cartridge it became the big 7magnum.It was advertised to be about 200fps faster than the 7mag and also faster than the 7mm Weatherby Magnum.It kept that lead for a couple of years until Remington,who also introduced the 7STW as a factory cartridge and chambered rifles for that cartridge came out with their own Ultra Magnum line of cartridges.The 7mm Ultra Mag bested the 7STW by around 200fps as Remington wrote in their introduction of their new cartridge.It's all about marketing.I remember when they did the comparison between the 7STW and the 7mm Ultra Mag,the velocity for the 7STW was less than what they showed for it when they compared it to the 7mag just a few short years before.Once again,it's about marketing your product.If you look,most of the 7mm Weatherby Magnum loads in the load books today,they even beat the 7STW loads listed.I realize the Weatherby is loaded to a higher pressure and their rifles have a lot of freebore,but really?I picked up a 7STW twelve years ago.It is a 1997 26" barreled Sendero rifle.Along with the purchase,I was given a box of Winchester Power Point ammo.I was working with H1000 and IMR7828 powder at the time and was finding it hard to get 200fps faster than my 26" barreled 7mag loads and it was taking about ten more grain of powder too.I ran a few of those 150gr Winchester factory rounds over my chronograph and I got a sizzling 3450fps out of those factory rounds.I got home and pulled a bullet out of one of the factory rounds and weighed the powder charge.I got 80.0grs.I did a little research and found that Winchester was using Winchester WXR powder for their loads.I know the factories usually use powders sometimes that is not available to the public,but I thought I'd give it a shot.I bought some WXR powder and was able to duplicate those factory velocities with that powder.I know you cannot find any load data for the 7STW that produces those kind of velocities today,but at the time they were marketing that cartridge,Winchester too was producing rifles chambered for it and they were loaded kinda hot compared to todays standards.But getting back to the topic of this post,with the powders we have available today,and experience handloader with a good rifle can safely exceed the velocities of many of the loads listed in some of the manuals today.