America's First .30-Caliber Service Cartridge
July 17, 2018
Last month I wrote about the .303 British and its long history of military service. This month I'll look at its United States counterpart: the .30-40 Krag. Dates of introduction and overall case design were very similar, but some differences are significant. Although prototypes were tested with blackpowder, the .30-40 Krag was perfected and issued as a smokeless-powder cartridge; the .303 British saw several years of service using blackpowder. The .30-40 had a very short service life (roughly from 1892 to 1903) unlike the .303 British (from 1888 to 1957). The .30-40 Krag never saw the transition from heavy, roundnose bullets to lighter, faster Spitzer projectiles that helped keep the .303 British cartridge militarily relevant for so long.
The ".30-40 Krag" name came later to avoid confusion with newer .30-caliber cartridges. Previously, it was commonly called the ".30 U.S. Government" or ".30 Army." After all, there were no other .30-caliber cartridges used by the U.S. military at that time.
The standard military bullet for the Krag was a 220-grain FMJ-RN that left the 30-inch Krag-Jørgensen rifle barrel at under 2,050 fps and under 2,000 fps from the 22-inch barrel of the Krag carbine. That was very close to the performance of the original 215-grain FMJ-RN bullets loaded in early .303 British service cartridges.
The .30-40 Krag is a true .30-caliber cartridge, with the same internal barrel dimensions as the .30-06 Springfield. Like its English counterpart, its rifles required generous chamber throats to handle long, blunt bullets.
The .30-40 and .303 cases almost suggest a common origin. The reference diameter forward of the rim differs by only 0.0023 inch. Rim diameters are close, too. The Krag case is longer at the expense of the body, creating one of the longest necks in the industry. It is just shy of a half-inch. An old friend called the Krag a ".30-30 on steroids," but the Krag predates the .30-30 Winchester.
SAAMI pressure guidelines for the Krag are lower than for the .303 British. The Krag's maximum average pressure (MAP) is 40,000 CUP compared to 45,000 CUP for the .303. Both service rifles share the single locking lug design, so you'd think they would share pressure assignments. Instead, the difference came down to metallurgy, not parts configuration.
U.S. Krag rifles had some fairly brittle metal for bolts and receivers. Military development attempts to improve velocity by loading to 45,000 CUP failed when cracks developed behind the locking lugs on too many rifle bolts.
Current SAAMI velocity guidelines have the Krag looking better than it did when in uniform. A 220-grain bullet has a nominal velocity guideline of 2,150 fps and the 180-grain bullet is at 2,420 fps. These are set in 24-inch test barrels.
My mentor in many things, Dr. Atticus James Gill, had a great fondness for the Krag. He liked both the quirky Krag rifle and the cartridge. Dr. Gill was a serious reloader and cast-bullet expert, and the .30-40 cartridge held all the attributes he liked: accuracy in the proper rifle, a long neck for cast bullets, and an affordable expenditure of propellant. I bought the Krag that I still own based on his enthusiasm.
Notice that I said "proper rifle" when talking about accuracy. At the time these rifles were made, primitive gauging technology and the inability to reproduce dimensions lot after lot produced some Krag rifles with other than the classic 0.300x0.308-inch barrel diameter standard.
I was offered an original Krag rifle in very fine condition, but for me, it had to be a shooter as well as a "looker." The bore looked practically unfired, but its groove diameter measured 0.314 inch. The largest .303/7.7mm component bullets of the time were 0.312 inch. I regretfully declined the purchase of that lovely rifle.
In civilian life, the Krag cartridge and rifle proved to be a hunting combo that was popular and successful. Heavy blunt bullets at modest velocity provided excellent penetration on big game. Peters sold a highly touted factory hunting load of the time that featured a 225-grain "Inner Belted" RN-HP bullet that was the forerunner of the famous Remington Core-Lokt bullet. It was perfectly tuned to Krag velocities and had an impressively thick jacket that would be at home among today's ultra-premium bullet designs.
The combination of a long neck and the efficient use of propellant makes the .30-40 a handloader's dream. Case life is relatively normal. Unlike the .303 Lee-Enfield action, the Krag bolt locks at its front, reducing case stretch. The neck makes this a great cast-bullet cartridge. Many .30-caliber cast bullet designs that look awkward in a modern cartridge were expressly designed to fit the Krag's long cartridge neck and barrel throat. When loading 150- and 165-grain Spitzer bullets, take advantage of the maximum cartridge length of 2.965 inches when seating. Keeping them closer to this maximum will help accuracy significantly.
Surprisingly, IMR 4350-class propellants do fine in the modest-capacity Krag case, especially with 180-grain and heavier bullets. Dr. Gill used compressed loads of H4831 based on pressure data he got from the NRA. He lost a bit of velocity, but the pressure readings were in the low 31,000 CUP range- very easy on cases and old metal parts.
The one caveat I offer reloaders is to choose your bullet based on feeding. I have examined plenty of Krag rifles, including mine, that are unhappy feeding Spitzer bullets. They feed roundnose profiles without issue. Your mileage may vary, so test before you create a pile of cartridges only to find out they won't feed smoothly.
The .30-40 must still have fans besides me. As of presstime, Hornady, Remington, and Winchester all feature a 180-grain factory load in their catalogs and still offer empty cases for reloading. This old soldier can still serve.