I'll try to keep this as short as possible, but include the meat of the subject. If you have any personal questions, my e-mail address is readily available, and I'll attempt to answer any questions you might have within the range of my personal experience and/or the available reference materials.
Our (the United States Government) first official bolt action rifle was the 1892 Krag Jorgensen Rifle adopted in surprisingly enough, 1892. This rifle supplanted the Trapdoor Springfield (Model of 1873) which had supplanted the Allen Conversion of our Civil War ("The War of Northern Aggression" according to my Confederate ancestors) muskets. The original Allen Conversion was just that, a reworked musket w/a sleeved barrel. Later versions were produced from scratch and all fired a "mouse gun .50 caliber" referred to as the .50-70 ctg. The "Trapdoor" came along at about the same time as the 1873 Colt Peacemaker Single Action, and the pair of them in either rifle or carbine length became our service weapons until about 1892. Springfield Armory and several U.S. Weapons outfits (Remington and Winchester in particular) had tried several experimental weapons (The Ward Burton 45-70 single shot bolt action from Springfield and a 45-70 magazine rifle from Remington) which were issued to the troops on an experimental basis.
By 1892, the choice had become the Krag, which in several variations (the '92, '94, '96, '98 and '99) became our issue rifle/carbine until the '03 was adopted (I have an 1898 rifle with a cartouche on the stock marked 1906). For those of you interested in the Krag, I recommend that you get a copy of Bill Brophy's book of the Krag. Dissatisfaction with the necessity of reloading the Krag with individual cartridges stuffed in a spring loaded port in the starboard side of the rifle, the U. S. Army "drooled" over the German Mauser which load from the top with 5 rd. stripper clips (there are several experiments out there in which Springfield modified the Krag to load from a stripper). Springfield started experimenting with the Mauser Patent in the late 19th century and had several experimental rifles on the drawing board by 1900.
In 1903 the so called '03 Springfield was adopted utilizing a ctg. firing a 220 grain bullet at approximately 2300 fps. The 30-40 Krag had fired the same projectile at approx. 2000 fps. and the increased velocity was considered necessary to compete with the Spanish Mausers the U. S. Troops had encountered in Cuba in 1898. The original Krag with its single locking lug would not accommodate the increased chamber pressures of such a "hot rodded cartridge" so the '03 was born. The original version of the rifle had a "horrid" invention (pirated from an earlier Trapdoor Springfield) called the "ram-rod bayonet"... a sort of "sish-ka-bob" device that doubled as a cleaning rod when not employed "skewering" the enemy. No less a personality than Teddy Roosevelt himself directed that Springfield Armory go back to a blade bayonet based on his experiences in Cuba and the use of the Night Attack by the Japanese in the Russo-Japanese War.
German experiments had produced the so called "spitzer bullet", a "pointy nosed" affair with a boat tailed rear end (a subtle improvement we were not to appreciate until after the Great War). The improved cartridge became the well known .30-'06 cartridge that was to become our military mainstay until about 1957... actually longer if you figure that the redistribution of the M14 for the M-1 wasn't completed until after 1965. The original ctg. was usually known as the .30 Government, but has since been (sometimes) called the .30-'03 to distinguish it from the .30-'06.
The original rifle was known as the U.S. Magazine Rifle, Model of 1903. They were fitted with a device on the left side of the receiver, known as the "magazine cut off". This was essentially the "full auto switch of the day"! The "powers that be" were terribly afraid that the troops would waste ammo with the "magazine rifle", so the "cut off" was " installed so that the magazine could be filled with 5 rds., the cut off set to the "off" position and the rifle used as a single shot until the "bad guys" came over the walls. At this time, you could switch the "cut off" to the "on" position and you could feed 5 successive rounds without reloading!!! Wow, real fire power eh what?!! Still you have to understand the "mind set" of the day. Don't forget there was no "helo resupply", all supplies, food, ammo, medical supplies, etc. had to be carried with you on patrol, in the lines, etc.... mule supply wasn't out of the question! This was a legitimate area of concern in the old days. Still we used to win our wars in that day and time, eh? Fire control was indeed a legitimate concern in that far off era, so consider carefully before you chuckle...
From the first, great concern over the uniformity of the bore diameter of the new service rifle prompted the use of a mechanical bore measuring device known as the "star gage"... (yes, that's "gage", not "gauge")... the device had "fingers" that extended into the lands and grooves to measure the size of the barrel. The Krag Rifles had suffered from a lack of uniformity and the "star gage" (circa 1905) was designed to correct the deficiency. By 1909 it was discovered that the more modern methods of rifling the '03's barrels had resulted in a product that would pass the "star gage" test in well over 90% of all the new rifles. Star gaging was discontinued for all rifles and thereafter only a percentage of those manufactured were run through the test to insure uniformity. With the advent of the National Match Springfield in 1921, all NM '03 were "star gaged" and all weapons sold through the DCM were issued with a "star gage" record. A barrel that was star gaged was marked with a small "sunburst" at 6 o'clock on the crown of the muzzle. Please remember that nearly all '03 barrels would pass this test so just because the '03 you own isn't stamped with the "magic star" doesn't mean it won't shoot! Weapons classified as Match '03s built prior to 1921 normally don't have the "star gage" stamp.
Springfield Rifles prior to the W.W.II buildup were built at both Springfield Armory and Rock Island Arsenal, utilizing two separate serial number ranges. By 1917 it was discovered that there were not sufficient '03s to arm the huge numbers of Americans who sprang from the necktie counters to the colors in the wave of patriotism that swept the country. The '03 was supplemented by the 1917 pattern Enfield rifle made by Winchester, Remington and Eddystone (a subsidiary of Remington). The 1914 Enfield had been being mfg. for the Brits. under contract in .303 British to supplement their efforts in France. A few minor changes and redesigning the Pattern 1914 to fire the .30-'06 ctg. resulted in the U. S. Rifle caliber .30 Model 1917. Strangely enough, the U. S. Army used more Enfields in France than Springfields (the famous sharpshooter Alvin York actually used an Enfield in winning his Medal of Honor!). The Marines utilized the Enfield in training, but turned them in when they went to the rifle range and took only 1903's to France. After the war, the M1917 was relegated to a limited standard status and the 1903 was reestablished as the standard issue arm.
Prior to 1918, there had been scattered reports of burst '03 receivers. A lengthy investigation into the incidents revealed that the forging of '03 receivers at both Springfield and Rock Island was being accomplished more as an art than a science. Those forging the billets of steel into receivers relied upon "eyeballing" the color of the billet prior to finishing. It turned out that under certain lighting conditions (cloudy days, etc.) there were definite differences depending on one's "eyeball", resulting in an occasional "brittle" receiver. Most were perfect, but a few of those that slipped by were suspect... unfortunately there was no metallurgical way of detecting the faulty receivers without destroying them and no way of correcting the brittle metal even if the receivers could have been identified. The metallurgical process was changed and the new receivers were said to be "double heat treated". The new process was begun at receiver serial number 800,001 at Springfield Armory (Feb.1918) and serial number 285,507 (May 1918) at Rock Island Arsenal. All receivers of these numbers or higher are known as "high numbered Springfields" and are considered to be above suspicion. Numbers below those listed are best fired with factory loads or better yet used as collector's items. General Julian Hatcher, then a young ordnance officer suggested drilling a hole in the left side of the receiver as a gas relief port to cut the incidence of burst receivers. While this was generally ignored by the Army, the Marine Corps took the suggestion to heart and many of the Marine Corps low numbered '03s of the era will be found with the so called "Hatcher Hole" in the left side of the receiver. After W.W.I, the Marines solved the "low number gun problem" by rebarreling them when sent back for refit, drilling the Hatcher Hole and reissuing them with instructions that they were not to be used for firing rifle grenades. The high numbered guns are extremely strong and never experienced any problems.
Minor design changes over the years included the addition of stock bolts to absorb recoil without cracking the stocks, minor contour changes to the handguard and removing the checkering on the buttplate (except for the National Match and .22 cal. training Models).
Stock variations (not counting experimental and .22 cal. Models) were:
Models of the 1903 Rifle:
These do not count the 5 different variations of .22 cal. "Gallery Practice Rifles" or Match Rifles (National Match, Style T, and International Match rifles, or Armory produced Sporters). Only one official (Army) sniper rifle was produced, the 1903A4 as above, although two different versions of Warner Swasey Telescopic sights were issued (1908 and 1913) and used to some extent during W.W.I. The Marine Corps produced their own version of a Springfield Sniper designated within the Corps as the Model 1941 Marine Corps Sniper Rifle. These were manufactured at the Marine Corps Ordnance people in Philadelphia utilizing National Match '03s mounted with 7.8X (usually mistakenly called 8X) Unertl Varmint type scopes. These rifles served the Marines throughout W.W.II and Korea and were excellent weapons. The same cannot be said for the M1903A4.
Several attempts were made to increase the firepower of the '03, the first being the Mark 1 made to utilize the so called Pedersen Device which simply plugged into the receiver in place of the bolt. A chamber insert (integral part of the device) filled the .30-'06 chamber and the weapon fitted to fire a sort of extra long .32 auto cartridge (the .32 auto is really .30 cal.). There was what amounted to a pistol slide on top of the device to cock and chamber the round. The device was semi-auto and marked the U.S. Pistol cal. .30, Model of 1918. A 40 round magazine snapped into the right side of the device at a 45 degree angle. The bullet weighed 80 grains and had a muzzle velocity of approx. 1300 fps. These were produced for the big spring offensive of 1919 which never occurred of course. The ballistics looked OK for trench warfare, but were recognized as obsolete after the war. Approximately 65,000 of the devices were manufactured and stored until the early 1930s when they were destroyed and the Mark 1 Rifles were returned to general service (a few of the devices survived, but most are now in museums). The second attempt (or maybe first) to increase firepower was a twenty round box magazine that plugged into the bottom of the magazine well in place of the floorplate. While it was an interesting idea, the magazine was solid enough to survive being run over by a tank and added almost 3/4 of a lb. to the rifle without even adding ammunition. The result was cumbersome and never very popular. Bill Brophy maintained that they were made for the "air service", but those I have seen were made after most aircraft were armed with machine-guns... in my opinion, they were made for the lads in the trenches.
I could go on for many pages on this splendid old rifle and just barely scratch the surface. For those interested in more details I recommend getting yourself a copy of Clark Campbell's "The '03 Springfield", Bill Brophy's "The 1903 Springfields" or Crossman's "Book of the Springfield". If you have any questions I have not answered, feel free to ask.
Incidentally, if any of you folks out there know the whereabouts of a genuine "Rod Bayonet '03", I'd be most obliged....