.300 wsm and .300 Win Mag whats the diff?

[mrnyman]

On Paper they seem to be the same ON PAPER, but are there any difference performance ?
Mind you i have never shot either round.

Just doing some research before i buy.

Thanks Nyman.

[Tomcat088]

On Paper they seem to be the same ON PAPER, but are there any difference performance ?
Mind you i have never shot either round.

Just doing some research before i buy.

Thanks Nyman.

The 2 cartridges are different, but not so different. From a sheer performance standpoint, the 2 are nearly identical, nearly. It's quite interesting, but with the lighter bullets like 155-180 grain, the .300 WSM will shoot those bullets FASTER than the .300 winmag will. The nice thing about this is that the .300 WSM will do it with less powder, which means less reloading cost, less heat on the barrel, which results in slightly less barrel wear. This is IF they have the same length of barrel, that being around 24". Now, when you get to the 190 grain bullets, the two will perform nearly identical, although the edge is starting to go to the .300 winchester magnum. Once you get get past 190 grain, the WSM will trail behind, and will not be able to achieve the same velocity that the .300 win mag will be able to with those heavier bullets; this being a result of the WSM having less case capacity. Most people don't shoot bullets over 190 grains, but if you intend to do so, it is a performance issue.

There are some other pronounced differences. The .300 winmag is built on a belted magnum case, meaning it has a belt. I'm not sure if you're familiar with belted magnums, but it is a little lip that sticks out towards the bottom of the case. Every other case in this photo has a belt in it, you should be able to see it.


On a belted magnum case, the cartridge headspaces off of that belt, and NOT the shoulder like many other catridges. The .300 WSM is NOT a belted magnum case, and therefore it headspaces off of the shoulder. If these are not terms that you're familiar with (headspacing, etc), please ask and myself and others will be happy to clarify. Either way, it's a difference between the two catridges. Because they headspace in different places, it also means that they tend to wear brass in different places. It does not mean that one is necessarily better than the other, merely that they're different.

Since the cartridges have different sizes and capacities, their powder columns are different. The .300 win mag has a long and narrow powder column, while the .300 WSM has a short and fat powder column. This does have some effects on how the powder burns. The main difference is that since the powder colum on the .300 WSM is wider, the flash from the primer will actually ignite more of the gun powder than it does in the .300 win mag. Some people say this results in consistency differences, although it's very hard to measure. I will say that most people, myself included, can't consistently shoot well enough to blame some slight differences in consistency solely on this issue. It is theoretically true though, that when more powder is ignited by the primer flash, it will burn and ignite more powder; resulting in a more consistent burn. This is why most people attribute the .300 WSM to be more efficient; meaning it can get the same velocities on light to medium weight bullets with less powder. You have to realize though that this is also just as dependent on the primers used, and even more so on the types and charge weights of the powders you are using. Either way, it is accurate to say that the .300 WSM uses less powder and can achieve the same velocities, so it is therefore more efficient, which has pluses in terms of heat generation, barrel life, etc; BUT it also has it's costs which I will get to later.

Some people will claim that the .300 WSM has less recoil than the .300 win mag, with similar loads (meaning similar bullet weights but same velocities), if the rifles weigh the same, etc. I think this is a bit of a stretch, and I think based on physics, if you're pushing a 190 grain bullet the same velocities, for every action there's an equal and opposite reaction; so I just see the recoil being very similar. The one thing that MIGHT affect the feeling of recoil is that they may have different impulses, because the powder ignites and burns at different rates because of the case shape. Either way, I've shot very similar weighted rifles with similar loads, and haven't really noticed a difference. Recoil is so subjective, this is something that is very hard to quantify, and not really something I'd base my buying decision on.

Another major difference, and many times a deciding factor of whether or not to go with the .300 WSM or .300 winmag is related to their actions. The .300 win mag is built on a long action, where as the .300 WSM can be built on a short action. The short action will weigh every so slightly less, and be a bit more compact, while the long action .300 win mag will be a bit longer and slightly heavier. Some people will claim there are differences in flex between long and short actions, I've done some posts on this before so you may want to search. Either way, it's pretty safe to say almost no shooters can shoot well enough to notice that difference, and the effect is negligable. The big difference though has to do with bolt throw. The bolt throw on a short action is very short, and therefore quite fast. The bolt throw on a long action is longer, and therefore even if you're moving the bolt just as fast, since it has a longer distance to travel, it will be slightly slower. This may or may not be something that matters to you (it doesn't matter to me), but some people are just more comfortable with a shorter bolt throw. I built my .300 WSM on a long action, this is a chore, but there was a method to my madness. The feed rails on the long magnum action had to be opened up slightly, and the front of the magazine had to be blocked off to accomodate reliable feeding. The reason that some of us do this though is when you want to reload long VLD type bullets into the lands. If you build a .300 WSM on a short action, and you want to be seating into the lands (which is where those bullets like to shoot more accurate at), the cartridges will end up being longer than the magazine length. When the cartridges are longer than the magazine length, this means you basically have a single shot rifle that has to be loaded with the bolt open every single time. On my long action, I made it so that the magazine length still had enough room so that you can seat the bullets into the lands and still have a repeater that feeds from the magazine. The problem with doing it this way is that it takes a lot of work to make the change, and you still have a long action length bolt throw on a short action caliber. You can't do this on factory rifle, but if you were building a rifle on a custom action, there are some custom manufacturers that make WSM actions that allow you to have a shorter bolt throw, but still have a long enough magazine to seat into the lands.

There is another LARGE aspect that should be mentioned, and this is related to barrel lengths. Because of the design of the cartridge and powder that typically shoot well in WSM cartridges, they usually need a longer burn length. Although heavy weight bullets will usually shoot better with slower burning powders, to get good velocities and consistency, there are some powders that the WSM and win mag both like. The big difference is that since the .300 win mag has more case capacity, and so it can get away with not quite burning all the powder in the case. In my experience this means that if you want a shorter barreled magnum, in the 22" or 24" length, the .300 win mag will usually have the edge. If you're shooting the WSM's in shorter barrel lengths, like 22-24", you usually won't get the WSM to keep up with the .300 winmag. It should be noted that magnums were designed to have a bit of a runway (long barrel), and that they perform best in longer barrels; but some people want a hunting rifle with a 22" barrel. Either way, it's my experience that most WSM's need at least 24" barrels, and they do best with 26" barrels or longer. The .300 win mag will get better velocities from the 26" barrel than the 24" barrel as well. It should also be noted that in the magnum calibers, a few inches can make a fair bit of difference in velocities; it's not like shooting a .308 where a few inches may not make that large of a difference. Either way, if you want a short compact rifle that will have better velocities, you may want a .300 win mag instead of the short magnum. If you want a shorter bolt throw, then you may want the short magnum. If you want more efficiency, and plan to never shoot the heavy bullets, you may want the short magnum. It's all a bunch of trade offs that you have to consider. I hope this has helped, let me know if you have any other questions or I need to clarify things.

I wanted to give you an idea of kind of the differences in sizes of bullets. I don't have a digital camera handy, or else I could just take a picture. This photo is actually NOT of .300's, but it's in 7mm's but the same comparison. This photo is basically like comparing a .308, .300 WSM, .300 win mag, and .300 ultramag.

From left to right 7mm-08, .280, 7mm WSM, 7mm Mag, 7mm Ultra Mag. You want to disregard the .280, and look at the 1st, 3rd, and 4th rounds mainly.

Notice that the 7-08 and 7mm WSM are basically the same length, which is how it is with the .308 and .300 WSM. Then you compare the 7mm WSM to the magnum, and it's slightly wider, but a fair bit shorter, same with the .300 WSM and winmag. Hope that helps.

[mrnyman]

Tom Cat, as usual thanks for your very educated reply, it was an education.
The main thing is that if i'm not going over 190 grain rounds they are pretty much equal, i really intend to shoot 180 grains so i should be fine with the WSM.

Also the WSM doesnt have that belt so i',m thinking it should be less difficult to reload when i started reloading.

Thanks, Nyman

[Tomcat088]

Tom Cat, as usual thanks for your very educated reply, it was an education.
The main thing is that if i'm not going over 190 grain rounds they are pretty much equal, i really intend to shoot 180 grains so i should be fine with the WSM.

Also the WSM doesnt have that belt so i',m thinking it should be less difficult to reload when i started reloading.

Thanks, Nyman

Howdy Nyman, you're quite welcome for the reply, glad that I could be of assistance. The WSM doesn't have the belt, but it doesn't necessarily mean that it's easier to reload. Although you do have to watch different places on the brass on the belted magnum. Anyway, you have to understand the differences in the barrel length though and what it has to do with the velocities. Out of a 22" barrel, even with 180 grain bullets, the .300 WSM isn't gonna be moving quite as fast as the .300 winmag. It might not be enough to deter you from the WSM, but it's something that you have to understand. The WSM needs the barrel length to get the performance. So it kind of depends on what you length of barrel you want, what your velocity exepectations are, etc. It should also be noted that since the WSM is fairly new, although popular, there aren't as many rifles chambered in it. Like if you were wanting a heavy barreled factory Remington 700 in .300 WSM, you're not gonna find it. You'd have to rechamber one of their other rifles for it. The problem with that is this, you'd be building a .300 WSM on a long actionand have to change up the action. If you built it on a .308, then on top of rechambering it, you'd also have to get a new bolt and have it headspaced properly, or you'd have to open up the bolt face on the .308. Either way, it's something else to consider, because you may want a certain style of rifle that Remington doesn't build. Just something to consider.

[mrnyman]

Thanks for the reply, I see barrel lenght is crucial on the WSM.

The gun i'm looking at is a Tikka in .300 WSM, i believe it comes in a 26 inch bbl. not sure so i will have to check with the dealer. It is definately 26 or 28 though.

Thanks, Nyman

[Yellowfin]

WSM means ammo is harder to find and/or more expensive. There's nothing that makes it worthwhile to not stick with the more established cartridges like .300 Win, 7mm Rem, or .30-06. Everything you hit with them all goes down the same and your shoulder hurts less with the latter.