congratulations on your first military surplus rifle. they are addicting to say the least. my first was 2 years ago when my brother in law sold me an enfield, now I have over a dozen of the buggers lieing around. Kraig gives a lot of good information. if you ever plan on competing with it then he is the guy t go to for advice.
now, for some original information:
when you post pictures, a full length shot, underside close-up of the floor plate and trigger guard, closeup of the left, right and top of the receiver will offer the most information for us to help you identify it with. if you are not comfortable posting serial numbers online go ahead and use paintshop to blur out the last 3 digits, we can still make a fairly accurate guess of manufacture date from that.
some markings to look for are on the top of the barrel right behind the front sight and underneath the bolt handle.
the A3 varies greatly from early springfield models. they use a lot of stamped parts to take the place of milled parts. this was necessary to ease the manufacture and speed up production. the sights are also different. the 1903,A1 and A2 all had leaf sights or 3 point sights, all mounted on the barrel. the A3 replaced the rear sight with a peep or aperture on the rear of the receiver. this gives a better sight picture and the added distance between the front and rear sight(sight radius) helps make more precise shots. the A3 was only made by 2 companies, Remington and Smith Corona(type writer manufacturer).
ignore my complete lack of capitalization. I still have no problem correcting your grammar.
I never said half the crap people said I did-Albert Einstein
You can't believe everything you read on the internet-Benjamin Franklin
Bean counters told me I couldn't fire a man for being in a wheelchair, did it anyway. Ramps are expensive.-Cave Johnson.