Even though the 1903 Springfield was adopted in 1903, when actually, after all the changes, did it officially began being issued to troops, who was first, branch, units, theaters? I did find this info:

"As further testing revealed that the M-1906 cartridge was effective with a shorter, all-purpose barrel length of 24 inches (610 mm) in length, the decision was made to issue the Springfield with a 24-inch barrel length to both cavalry and infantry forces, an idea already adopted by both the British and German armies"

If regiments heading overseas, to the PI for example in 1904, would they have embarked with still the Krag carbine?

Thanks

Ed