Bob: As I recall, the Pancho Villia Mexican "Revolution" so-called ( I guess old Pancho would qualify as a "Terrorist" these days) happened around 1915.This was pretty much the "swan song" of the U.S. mounted Cavalry as a viable tactical branch of the Military. Horse Soldiers (I think the term "Dragoon" had become pretty much obsolete by the end of the Civil War) at least the US Regulars, were typically armed with the 1903 bolt-action Springfield rifle (the .30-40 KRAG was the last Army weapon to be issued in seperate Infantry "Rifle" and Cavalry "Carbine" configurations). The saber had been replaced, at least for Enlisted Cavalrymen, with the then-standard issue 17" blade bayonet, and the venerable (then brandy-new) M-1911 "Army .45" semi-automatic pistol was the regulation sidearm.
By 1915 the Regular Army had pretty much switched over to the M-1903 from the M-1896 "Krag" of Spanish-American War fame, and the State National Guard Units had generally scrapped the old "Trapdoor" .45-70 blackpowder single shot breechloading muskets & Carbines (such as the ill-fated Custer/ 7th Cav. Expediton was armed with at Little Big Horn) for the hand-me-down Krags. Most of the "trapdoors" (so named because of their front-hinged breechblock which lifted up at the rear for ejection of the fired case and reloading)were sold as surplus to outfits like "Bannermans" of NY City. Back then you could pick one up for the price of a good cigar; today a decent Infantry trapdoor will fetch up around $1,000 and Carbine, depending on vintage, much more.
Oddly, even though many of the American Military arms were designed and made at the Springfield Armory (as you correctly point out)since the early part of the 19th Century (I could look up the exact date if you're interested), the Model 1903 and it's WW-II version the M-1903-A3 (plus a few other variations such as the "Sniper" rifle seen on "Pvt. Ryan") were the only ones popularly and reverently (among Target Shooters and Old Marines, anyway) known as "The Springfield". Essentially a modification of the German Mauser design, the Springfield earned a reputation for ruggedness, reliability, long range accuracy, and knock-down power (as well as shoulder-bruising recoil).
With the advent of the M-16, US military weapons were and continue to be "contracted out" and Government Armories such as Springfield are a thing of the past. I understand that it is now a National Historical Site, and hope to visit the famous Museum there some day.
Who knows; perhaps they have a copy of the song!
I have heard a contemporary sort-of-C/W song which I think was called "The Gringo Pistolliero"; It was pretty neat, and I wish I remembered who did it - never heard it again. It was based on the "Pancho" affair, and involved what i think was a fictional story of a US Army Officer who takes up the challange of a Mexican Banditto to a gunfight; the "Gringo" steals into the enemy camp, having taken out his Sentry 600 yards away on a hilltop with "..a bullet from the Springfield of the Gringo Pistolliero", and proceeds to whip serious butt on the bad guys with his brace of 1911's. Both weapons were actually quite capable of that sort of performance in the hands of a competent Shootist. Of course our Hero then rides off to the North with the fair Senioritta in less time than it takes to reload.
Could this possibly be the same song?