Serial Number 19101 puts production in late 1895 to early 1896.
That would be consistent with the "Model 1894" marking on the receiver. These were originally made with full-length cleaning rods, and thin, flat buttplates with no trap in the butt. Later, the vast majority of these were updated to the Model 1896 specs, by filling the cleaning rod channel with a walnut dowel, and modifying the butt. (Unmodified Model 1894's are one of the "holy grails" of U.S.military collecting.) Check to see if there is evidence of a filled cleaning rod channel.
Kind of a cross between a Philippine Constabulary (stock) and an NRA Carbine (sight.)
Yes, the shortened front end definitely looks like a Philippine Constabulary carbine. Here's what the relevant web site has to say about it:
"Unique to only the Philippines, the Krag full length rifles were modified and cut down to a shorter size at the POD (Philippine Ordnance Depot) in Intramurous. The original purchase price for each Krag, $6.00. The Krag Carbine would also be short lived, they would later be replaced by Springfield M1903 rifles by 1910 (but Krags would still be in service until 1917). Less than a handful of these Philippine Constabulary Krag Carbines exist today. Making them the mostly highly sought after and prized rifle of all Krag models by gun collectors and enthusiasts."
http://armasdefilipinas.blogspot.com/2011/07/m1899-philippine-constabulary-krag.html
(Additional pictures at that site.)
Regarding the rear sight, that's definitely not an M1903 Springfield sight, but rather one of the several different types of original Krag sights. (Krag sights are a study in themselves.) It's definitely missing the wood handguard around the rear sight, which is matched to the particular type of rear sight.
So what we appear to have here, then, is a double alteration. First, it was an M1894 converted to M1896 specs, and, secondly, it was converted in the Philippines to a Constabulary Carbine. Looks like you got it for a steal.
Edited to add: Or, more likely, it could be a rifle altered by the government for school / cadet use. According to Bruce Canfield (quoted on another forum), there are only one or two authentic Philippine Constabulary rifles in the U.S. On the other hand, most of those school rifles had the later M1902 rear sight. Yours appears to have the original M1892 sight. Needless to say, there's a lot of confusion regarding PC rifles.
Repro handguards are available. Even the repros are pricey.
http://www.partsforantiqueguns.com/Krag (Springfield) Upper Handguards.htm
BTW, the handguard is held on by two spring clips, that are riveted to the handguard. The easiest way to install this, without scratching the barrel, is by removing the bands and the rear sight (the sight is fastened with two screws, and is readily removable), and sliding the handguard rearward from the front of the barrel. Then you reinstall the sight and the bands.