+1 to emcon, the magazine disconnect, which also serves as the bolt release is on the upper left side of the receiver and the safety is on the top-rear of the bolt.
switching the magazine disconnect to on makes the bolt only open enough to single feed rounds while failing to engage the rounds in the magazine, this was deemed necessary because many felt that if you gave a soldier a gun full of ammo he would waste it so it was common practice to order men to single feed only and save the ammo in the magazine for charges. switching it off allows the bolt to slide all the way to the rear and engage the ammo in the magazine while flipping it to a center position allows you to remove the bolt... it took me several months before I found out what the heck that thing was for besides bolt release.
If it is a scant stock, does that mean its more of a M1903A1?
yes and no, but mostly no. rock island armory shut down before the introduction of the A1. the S under the mag disconnect should mean springfield but again I am not an expert on stock marks and have already been proven wrong on this thread once. if it is a springfield stock then it is fair to say that this gun saw a great deal of refits. the A1 was supposed to have the full pistol grip or C stock and the only guns I've seen with the scant stocks are guns that had to have new stocks made. it's a semi pistol grip stock so it is not an A1 and it predates the A1 change over so it is not an A1 however it should have the straight stock with grasping grooves to make it a true blue 1903 which it does not have so the simple answer is kindof but not really.