As an old WW I issue rifle, alot came back as keepers. It is one of the better 30 caliber whitetail cartridges, which had a little more kick than a 30/30, because it was supposed to have 10 grains more powder. Modern Powders don't use the same recipe though.
The Krag was Spanish-American War. In WWI, we used the '03 Springfield and M1917 Enfield.
I dont usually get into debates concerning the history of some calibers.
What I said is that it was WW I issued, which it was. And it was still issued for duty in WW II. Both of which is why so many came back to end up hunting deer.
Below is a copied 30/40 Krag history from a reliable sorce on the internet :
The Rifle
The Krag Jorgensen rifle was originally designed by Captain Ole Hermann Johannes Krag, who was the director of the Royal Norwegian Arms Factory at Komgsberg (Kongsberg Våpenfabrikk), and Erik Jørgensen, also of Kongsberg, Norway.
This rifle was chosen by a US military board which convened to find a new service rifle to replace the .45-70 Springfield single-shot rifles then in service. The board first met in New York in December of 1890 and concluded their proceedings in July of 1892. They compared rifle designs from Lee, Krag, Mannlicher, Mauser, Schmidt-Ruben, and about 40 other military and civilian designs. The trials were held at Governors Island, NY.
While it was adopted in 1892 as the military rifle of US forces, it was not produced until 1894. Because the adoption of a foreign design upset some of the American inventors of competing rifles, the government was pressured to conducted a second round of tests during April and May of 1893. None of the other rifles passed the testing and the Krag was then put into production. According to government records 442,883 Krag rifles and 63,116 carbines (these figures vary slightly depending on the source) were eventually manufactured by Springfield Armory with a $1.00 royalty for each rifle going to the two inventors. The Krag, was also adopted as the service rifle of Norway as the M1894 in 6.5 x 55 mm, and in 8 x 58 mm R (rimmed) by Denmark as the M1898.
The Krag was the first US rifle to have the top of its barrel covered with wood for a handguard. While it is known for having the smoothest action of any rifle, its one locking lug action was not as strong as some of the other designs which utilized 2 or 3 lugs and made it susceptible to group stringing with wet ammunition because of unequal bolt face force. Its side mounted magazine was slow to load but the slowness of reloading was not viewed as a shortfall. At the time, the US military philosophy still placed great emphasis on precise aimed fire and looked upon the magazine as a reserve. (While high volumes of fire are now all the rage, and while they serve to allow mobility of force, it is interesting to note that, even in this day and age, when the military needs results it is the precision rifleman armed with a bolt action rifle that is called upon to do the job.)
The ballistics of the .30-40 cartridge were not equal to those of other available military rounds including the 7 x 57 mm Mauser used by Spanish forces. It should, however, be noted here that the 7 mm Mauser was used only by the elite Spanish regular forces. The local troops and militia units were armed mainly with Remington Rolling Block single shot rifles in 11 mm (.43 Spanish) which fired a 387 gr lead bullet at about 1340 fps and which was inferior to even the US .45-70 round.
The Krag, "U.S Magazine Rifle, Model 1892," or as it was often referred to, "The .30 Caliber Springfield Rifle of the Krag-Jorgensen Pattern" was made in several different models and variation during its 11 year service life. All models were fitted with 4-groove .308" diameter barrels which had a 1:10 " twist. I have been unable to find any accuracy standards but the rifle was deemed to be "effective" at 600 yards against infantry and 650 yards against cavalry.
As an interesting aside, in spite of its "slow to reload" magazine, War Department records indicate that it was possible for a skilled shooter to fire 43 aimed shots in 2 minutes using the rifle as a magazine fed repeater and 42 shot in the same time as a single loader. These times were recently confirmed by a correspondent from Norway who informed me that in a national match the 3rd place winner got 27 hits at 100 and 200 meters in 50 seconds using a Krag rifle.
Despite all of its shortcomings the Krag rifle served faithfully in the Spanish-American War (1898), the Philippine Insurrection (1898 - 1904), the battle of Tagalii, Samoa (1899), and the China Relief Expedition--also known as the Boxer Rebellion (1900). It also was issued for guard duty service during both WW I and WW II.
The Krag rifles utilized by US Forces during the Spanish American War were the M1892 and M1896 models. While many of the Rough Riders carried their own arms, their government issued rifle was the Krag M1896 carbine since they were considered to be cavalry (dismounted).
