Adventures with the .300 Winchester Short Magnum

Guns Magazine, June, 2003 by Charles E. Petty

This is a year for lots of new cartridges with short in their name. This offers the hunter and handloader a wide array of new opportunities. But I also know how frustrating it must be for readers to see articles about guns or cartridges that are really a year or more from reaching the shelves of gun shops around the country.

Winchester announced their .300 Short Magnum in 2000, but as I write this over a year later we're only now beginning to see them in stores. And on the heels of the Winchester short .30 comes news of .270 and 7mm variants from Winchester and short magnums in .30 and 7mm from Remington.

Idea Whose Time Has Come

This is one of those things that makes me wonder why it took so long. The superior efficiency and accuracy of short, fat cartridges has been forever proven by the families of PPC and BR rounds that equal the performance of much larger cases. But we've also got a paradox, for it wasn't too long ago that the big news was the family of Ultra Mag cartridges from Remington.

Those are big, fat cases that are loosely based on the .404 Jeffrey. These are beltless magnums and capitalize on the dislike of belted cases that seems to be growing. But for our purposes their effect is profound because they provide a parent case for the series of short cartridges we're beginning to investigate.

It's reasonable to ask just what the short cartridges will do for us. In my opinion, a number of good things. With the short magnums we can duplicate--or come real close--to the big magnums with a whole lot less powder, a bit less recoil, and generally improved accuracy.

Test Bed Rifle

My adventure with the Winchester .300 WSM begins with a Winchester Model 70 rifle with a 24-inch barrel and topped with a beautifully bright Kahles 3.5x10 scope. As it turns out this is one dandy combination. Even though this is a hunting setup, the accuracy potential I see makes me want a heavy varmint style rifle to work with. It is also my first visit to one of the new versions of the old, controlled feed, Model 70 action. Frankly, I like it.

New cartridges like this are wonderful opportunities for the handloader but they can also be minefields for the unwary. The factories are not going to give us much in the way of hand-loading help so we have to depend on information from the component vendors to find a place to start.

Hodgdon Powder always seems to be first in providing loading data for new cartridges and they had .300 WSM data before anyone else. Then further data began to appear here and there. GUNS has the philosophy of waiting for production guns, so, since I don't have to always rush to meet a deadline, it's possible to try more load combinations.

Of course you can also go overboard with endless experiments so I chose to work with bullets of 150, 165 and 180 grains, and limit the number of powders to four that I know pretty well and think will be suitable for the cartridge. Even so that's quite a bit of loading and shooting and once more my buddy Bob Maddox helped with the shooting chores.

The first step in any process like this is to see what the factory ammo will do. At this time Winchester offers loads with the 150-grain Ballistic Silvertip, a 180-grain Fail Safe, and another 180-grain loading with the Power Point bullet. Obviously we want to look at the factory velocities in comparison with the .300 Winchester Magnum. The published factory velocities are essentially the same.

Living Up To The Hype

We quickly established that Winchester really did duplicate the .300 Win Mag. in the short case. The important data here is the comparison of the actual velocities from the Model '0 to the published numbers for both cartridges. The agreement is positively wonderful. Please don't think that ten feet per second here or twenty there makes any difference.

As far as I'm concerned when we work with something brand new like this my primary goal is to find handloads hat duplicate the factory velocities. When more pressure tested data is available it might be possible to exceed them little, but prudence doesn't allow that just yet. The available data comes close but doesn't quite get there.

The beauty of the short-fat cases is their efficiency. By this mean they will deliver a specific velocity with less powder than their full size counterpart. One easy way to appreciate this s to simply divide the velocity by the weight of the powder charge This gives us the velocity achieved per grain of powder.

We could use this to calculate a change in efficiency as a percentage and, doing this, I found it to be from 5 percent to as ouch as 14 percent with the lighter bullets showing the biggest increase. And, since we're burning less powder, recoil should e lighter too. My shoulder couldn't detect the difference but lie computer did. Keeping everything except powder charge constant it told me recoil was reduced by no more than 2 ft/lbs.

The Model 70 is an 81/2-pound rifle with a sporter weight barrel, so my accuracy expectations were not high. I was quickly and happily proven wrong. Everybody says they want a hunting rifle that is capable of minute-of-angle accuracy but - as they come out of the box - not too many are. This one is.