Gentlemen,
I hope that you may find the following interesting, and informative.
Although this manual pertains primarily to the M1903, The following is  contained in the appendix:
The following modifications of the Revised Infantry Drill Regulations are prescribed for troops armed with the U.S. Magazine rifle, M1898.
54. 1st. to prevent accidents the magazine and chamber are to be opened and examined, when details, detachments, and other bodies of troops are first formed, and again just before they are dismissed.  In the commands the word CHAMBER refers to both magazine and chamber.
3rd.  the cut off is to be kept turned down except when using the magazine.
Lastly, and I found this to be very interesting to me as a new comer to the ranks of the M1898 rifle shooters.
146.  The rifle can be used as a magazine rifle by turning the CUT OFF up.  the use of the rifle as a magazine rifle is, however to be regarded as exceptional.

1stazmilitia

A significant reason the Krag - Jorgensen design won out in the U.S. Army trials, in the early 1890s, was the ease of using it as a 'single shot' arm, while holding the magazine in reserve.

It's important to remember that the Krag was replacing the single-shot Trapdoor.  One of the things that put the nail in the coffin is the Spaniards rate of fire, while US troops were firing single shot!  The Mausers were fired quicker, AND reloaded quicker than the Krag... and significantly quick than the Trapdoors that MOST of the troops in Cuba were using! 

Not only were the Trapdoors single shots, but the Spaniards filled the clouds of BP smoke with bullets.  Not sporting.

But the Army had a long history of preparing to fight the last war.  When looking for a smokeless powder rifle, they did not really think about fighting a European military force in a protracted (?) ground war.  The minds of those making decisions were set on the Indian Wars type of fighting, a series of small quick fights for which the Krag would have been ideal.