Thoughts on rifle case neck length.
The neck length of smokeless rifle cases doesn’t change as often as dress length in the fashion world, but it does change, and for valid ballistic reasons. Understanding those reasons can help handloaders make the correct choices for their shooting needs.
When smokeless powder first came into general use, necks started out long because bullets were long. Most early smokeless rifle cartridges, especially military rounds, featured very long roundnosed bullets, because cartridge designers believed they were necessary for penetration. Soon, however, a trend started in both military and hunting cartridges toward much lighter, pointed bullets at higher velocities, due to the obvious advantages of flatter trajectory and longer range.
In less than 20 years, the light lever-actioned hunting rifles favored by deer hunters evolved from the .30-30 Winchester, a long-necked case shooting relatively heavy bullets at 2,000 fps, to the .250-3000 Savage, a short-necked case shooting light spitzers at 3,000 fps. This gave sporting magazines another debate to fill their pages, but both cartridges survived, since sporting goods stores can just keep adding different kinds of ammo to their inventory.
Still, most cartridges had longer necks than many later designs, partly because rifle manufacturing was still evolving. If some company designed a new cartridge, they could use a new rifle action for that specific round. The history of smokeless rifles is crowded with actions such as the 1903 Mannlicher-Schoenauer, so specialized it’s extremely difficult to convert to anything except the original 6.5×54 cartridge.
Eventually, however, rifle actions became more standardized. Most bolt actions came to resemble the 1898 Mauser in size and form, since they were designed to accommodate rounds that worked in the 98. Similarly, the most popular lever-action designs of the early 20th century were the 1894 Winchester and 1899 Savage, so most new lever rounds were designed to work in those actions.
Most early smokeless cases, such as the .300 H&H, had long necks
because a lot of early bullets were quite long.
Most modern .300 magnums, such as (left to near right) the.300 Winchester Short Magnum, .300 Winchester Magnum and .300 Remington Ultra Magnum have short necks, to increase powder capacity as much as possible in a given magazine length. The .30-378 Weatherby (far right) has a longer neck because it’s designed for the very long Mark V Weatherby action.
To gain the extra velocity possible with new and improved powders, the newer cartridges became fatter, with shorter necks. The .300 Savage is a perfect example. Appearing shortly after WWI in the Savage 99 (and Savage’s ahead-of-its-time short-bolt action, the Model 1920), the .300 was the .30-06 case shortened, with a steep 30-degree shoulder and a very short neck. When loaded with newer powders it came very close to reaching the pre-WWI .30-06 velocities of 2,700 fps with 150-grain bullets and 2,500 with the 180, but in a much smaller case.
Many later cartridges followed this design strategy, crowding as much powder space as possible in a certain magazine length. Dozens of examples exist, including both the .300 Winchester Magnum and its 21st-century version, the .300 Winchester Short Magnum. The .300 Winchester is obviously longer and not as fat, but within the design parameters of 1963 (it had to have a belt and fit in a .30-06-length magazine) it put as much powder space as possible behind a .308-inch bullet.
The .300 WSM lost the belt, so manages to squeeze almost as much powder space into an even shorter magazine. In fact, the .300 WSM has just about exactly as much powder capacity as the .300 Holland & Holland Magnum, a much longer round in both body and neck.
Old-time handloaders and gun writers such as Townsend Whelen often complained about the short necks on newer cases, for three reasons. First, short necks didn’t allow as much versatility when loading various bullet weights. The relatively long neck of the .30-06 made it easy to load either 150-grain spitzers or 220-grain roundnoses, while the short neck of the .300 Savage made this almost impossible. Today most of us don’t shoot such a wide variety of bullet weights from one rifle, but if we do a longer neck does help.
Second, they felt a very short neck didn’t provide enough grip for the bullet. A commonly quoted rule of thumb, even today, is for bullets to be gripped by at least one bullet-diameter of neck, meaning a neck at least 0.3-inch long for any .30 caliber. This rule might be valid in ammunition designed for automatic weapons, but the 0.221-inch neck of the .300 Savage proved it wasn’t necessary in sporting ammo—and the 0.264-inch neck of the .300 Winchester Magnum has been working fine for half a century now.
Third, they believed short necks reduced powder space, due to the shank of the bullet extending below the neck. This isn’t true, since the rear end of a bullet takes up just as much room inside a long neck as it does below a short neck—and below a short neck the bullet’s base is surrounded by more powder, instead of brass. This is one of the ways short modern cartridges provide more powder room behind the same bullet.
If you shoot a lot, especially with a warm barrel, a longer case neck reduces throat erosion.
However, a short neck doesn’t always work with the very long, streamlined bullets that have become so popular for all kinds of shooting. With a short-case neck and rifle magazine, the bullet’s ogive often ends up being seated well behind the case mouth.
As a result, some recent wildcat and factory rounds have even shorter, fatter cases but longer necks. Longer bullets won’t end up with the ogive inside the neck, yet the cartridge will still function in a standard magazine. A prime example is the 6.5 Creedmoor, but a longer neck on a shorter case is also the reason some shooters prefer the 7mm Remington SAUM to the 7mm Winchester WSM.
A secondary effect of a longer neck is reduced throat erosion. Most erosion occurs right in front of the case mouth, where powder gas is hottest. A longer neck essentially functions as a brass shield, protecting more of the chamber throat. This is probably why the .220 Swift doesn’t burn barrels out any quicker than the .22-250 Remington, even though the Swift has about 8 percent more powder capacity: The Swift’s neck is 0.302-inch long, while the .22-250’s is 0.264.
If you’re a typical big-game hunter, who only shoots 50 to 100 rounds a year and has zero interest in handloading target bullets, one of the relatively short-necked rounds will work fine. But if you do shoot a lot, whether at targets or varmints, a longer-necked round will extend barrel life somewhat, and allow more flexibility in bullet seating.
By John Barsness