I believe the issue was more the rifle than the ammo on the battlefields of Cuba. Loading with stripper clips was a huge advantage over the box magazine of the Krag.
That was certainly one of the issues. It's much faster to load five rounds with a stripper clip than it is to load five loose rounds one at a time. I believe, entirely subjectively, that it has to do with the military have a difficult time wrapping its head around new advances.
In the Civil War, General James Wolfe Ripley was the Chief of Ordnance for the Union Army. The phrase "that dumb f _ _ k" is certainly applicable to him. The wrong man in the wrong job at the wrong time. Metallic cartridges and repeating rifles -- the Henry, the Spencer, the Burnside, even the Colt Revolving Rifle if configured for metallic cartridges -- were all available. The Confederacy had no ability to produce rifles using metallic cartridges; the Union did. In
Stars and Stripes Forever, the late Harry Harrison had a character explain the difference between a muzzleloading rifle-musket and a repeater to Queen Victoria thusly: If your regiment has a rifle that can fire three rounds a minute and your opponent has a regiment with rifles that can fire 30 rounds a minute,
in effect your opponent has ten times the soldiers on the field. Your regiment will be wiped out in short order.
If Ripley had not been such a hidebound jackass more concerned with soldiers wasting ammunition --and how many times have we heard
that old chestnut when changing from one rifle to another? -- and had ordered say, the Spencer into full production, the Civil War would have lasted perhaps one year because the Union Army would have slaughtered the Confederate Army on the battlefield; see the explanation in the previous paragraph. But Ripley refused to see the facts in front of him. The only Union units that got cartridge rifles in quantity were the privately-equipped Sharpshooter regiments and some Cavalry regiments late in the war. I mind me of one battle during the Shenandoah Valley campaign where an understrength cavalry regiment armed with Spencers stopped a Confederate cavalry force of three regiments butt-cold by taking up dismounted defensive positions and letting them have it with their Spencers. The Johnny Rebs retreated in disarray leaving a large number of dead behind them and did not try to force the passage again because they were convinced there was a Union division holding that position. The same thing would have happened infantry versus infantry, if Ripley had not been an idiot. The war would have been shorter and with a lot fewer Union casualties, had Billy Yank been equipped with a repeater instead of a rifle-musket.
The U.S. Army made a similar mistake in 1873 at the competition supervised by Brigadier General Alfred Terry, a Civil War hero and later a respected Indian fighter. 99 different rifles were tested, including repeaters. The winner was the Allin "trapdoor" single shot cartridge loading system; single shots were allegedly more reliable than repeaters. (I'll pause for a moment while we all laugh.) And I am
sure that the fact the Army had three metric butt-loads of Springfield rifle-muskets in storage that could be converted into single shot Springfield Trapdoor Rifles and Trapdoor Carbines for a whole lot less money per unit than it would cost to buy repeaters like the Winchester Model 1873 had
nothing at all to do with that decision.
Comes the 1890s, and the Army is looking to upgrade to a magazine-fed battle rifle. A competition was held with entries from Lee, Krag, Mannlicher, Mauser, and Schmidt–Rubin. The Army selected the Krag-Jorgensen, because the generals liked the fact the magazine could be topped up without opening the bolt, meaning the soldier could continue shooting while reloading (at least in theory). They also believed that a lower reloading speed versus stripper clip loading would encourage soldiers to conserve ammunition. (And where have we heard
THAT before?) Their theory was disproved as I have said elsewhere in the thread by the US Army getting the hell shot out of it in Cuba by Spaniards equipped with stripper-clip loaded Mausers. The Krag magazine was a good system, but one that had been overtaken by time before it had a chance to prove itself in battle.
The stripper-clip loading system ruled the rifle roost for the next half-century. The first serious attempt to depart from it with a semi-auto longarm was with the prototype M-1 Garand. John C. Garand chambered the rifle in .270 Win and equipped it with a detachable magazine generally similar to that of the Browning Automatic Rifle, presumably on the don't-reinvent-the-wheel theory. The Army didn't like that, again claiming it would encourage soldiers to waste ammunition. (Holy Mary, Mother of God, didn't any of these decision-makers ever get shot at as junior officers?) Douglas MacArthur, the US Army Chief of Staff at the time, didn't like the idea of changing the rifle caliber. He
HAD been shot at, and shot at a lot, in World War I. (He did not come by his Distinguished Service Cross because he stayed safely in his headquarters.) He liked the idea of the machine guns and rifles having the same round, knew what the .30-06 round could do, and knew the Army had mountains of .30-06 in storage. Garand had to go back to the drawing board, up-gun his design to .30-06, and come up with a loading system that was not based on either stripper clips he saw as obsolete, or on the detachable magazine he saw as the wave of the future. The result was the en bloc clip that is the trademark of the M-1 Garand rifle. But you notice no one else adopted the idea.
Then, of course, the US Army woke up and smelled the coffee after the Korean War, realizing it needed a battle rifle with a detachable magazine, but preferably one that they did not have to completeluy retool to make. Essentially, they adopted the rifle John C. Garand had presented to the Army back in 1932, but in the new 7.62 NATO caliber, the downsized .30-06 round; same bullet, better powder, smaller case, similar performance. The decision-makers at that time had been in World War II as company and field grade officers, and been shot at a lot, and at last did not make the argument that a large capacity magazine would encourage the line-animals to waste ammo. Their attitude regarding the M-14 seems to have been, "Waste ammo, not lives."
Then the M-14 with its powerful 7.62 NATO round was replaced by the abomination known as the Poodle Shooter firing a round half the states in the Union won't allow you to use in deer-hunting; but that's another story.