The '03A3 is a modernized version of the '03, and has a much easier-to-use rear-mounted peep aperture sight.  The cost-cutting changes did not hurt it at all; in fact the changes were improvements that allowed faster, less-expensive production without sacrificing reliability, or battle effectiveness.

One gives up the more complicated, but more versatile, barrel-mounted rear sight for a rear sight that is much quicker and more intuitive to use.  It's also much easier to use by people with older eyes, compared to the original rear sight, which was intended for young, sharp, eyes only.  To my mind, the newer rear sight is an overall asset to the single rifleman.  The earlier rear sight might well have been a benefit if one was in a sizeable unit whose members were trained to use the earlier rear sight.

To my mind, the only defect of the '03A3 is the elimination of the detachable magazine floor plate.  The earlier version allowed the user to open the bottom of the magazine, and remove unexpended rounds.  The newer versions requires the user to manipulate the safety lever to a certain point, and then use the bolt to remove unexpended rounds.  this is potentially unsafe, and also has the potential of damaging the ctgs needlessly  The earlier method was more costly, but safer IMHO.  The earlier construction also allowed easier cleaning of the rifle. 

Aside from these personal quibbles, the 03A3 is a fine rifle.  Just be sure to find a USMC front sight protector.  Army version is useless.  The unprotected front sight of all the '03 rifles has been documented as the most common cause of the rifle being returned for repair.  Ordnance Went Up Front by Roy Dunlap

I was privileged to be able to shoot alongside some (then) old-timers shooting various iterations of Army and USMC Match grade '03 Springfields.  Some had the usual Army upgrades to the rear sight, some had the USMC rear sight. For target range use, most of them had modified their front sight base to accept a somewhat wider front sight blade. Perhaps that was on account of older eyes, but most RKIs agree that the original Springfield front sight was too thin for combat use.  It's being entirely unprotected being a far more serious defect, in combat. 

You Springfield users go find a USMC front sight protector.  They are not cheap.       

I LOVE my '03A3. I find that really narrow front sight is excellent for precision. My wife loves it too.

I was kicking myself for not getting one when the CMP had them. At that time, you could get a decent example for $600 or less. This was NOT long ago. After they ran out the prices went crazy, now to touch an un-dicked-with example they seem to run $850+. I couldn't justify that. My friend had a drill rifle Remington receiver from Gibbs, a NIW Remington bolt, and a NIW Remington barrel. Bought all that from my buddy, took them to a local smith known for working with USGI rifles and he barreled and headspaced it for me, and I finished the rifle out with a NOS scant stock from Numrich and a Sarco parts kit, which turned out to have a lot of junk repro parts in it. I ended up replacing all the repro parts except for the rear sight, which ironically is fine and the most complex part. So in the end I have about $850 in it.

Regardless, it's gorgeous and shoots like a dream. I can shoot it better than many scope-equipped rifles I own.

The '03 Springfield was a copy of the '98 Mauser.  Springfield Armory (Gov't entity, then) deliberately made some changes to the original design, all of which, IMHO, were intended to forestall Patent infringement lawsuits.  As it turns out, this was unsuccessful, and after WWI, the US gov't agreed to pay Mauserwerke quite a bit of money for patent infringement.  IMHO, all the changes the US made to the '98 Mauser were, at best, of questionable value, and some, like the thin, unprotected front sight, were negative changes.   Both rifles are controlled-round feed types. 

Whether the M1917 rifle, with which the majority of US WWI troops were equipped, was better or worse then the '03 Springfield is the subject for a different thread.

Let's keep this thread focused on the '03. OK?      

You basically push the 6th round down into the mag even though it won't below the feed lips. That way it still rises below the extractor as you close the bolt.

Agree.

Thin Front sight for precision on the Shooting range, Thick Front sight for visibility on the two-way shooting range.

Holder