Well, your build looks pretty good. As far as accuracy, I noted some things that may have escaped your notice:
1) the gun barrel would have rested completely on the gun lock -- not just above the upper clips
http://www.toadmanstankpictures.com/m4a3_02.jpg2) the real M4A1 gun tube did not have the step as Italeri molded it. It should be smoothed over with putty. (Italeri incorrectly used a postwar de-militarized tank with a modified gun tube as their pattern)
3) the horizontal bolt strip at the top of the nose/transmission is integral to the nose/transmission and not part of the hull.
Here's a photo of an M4A3 but you can see what I mean about the bolt strip:
http://www.toadmanstankpictures.com/m4a3d_05.jpg 4) the antenna is British style -- not American.
5) and finally, the stiff Italeri tracks don't allow you to accurately depict the tracks as they were very tight on the real thing -- no sag would be evident.
Have a look at this list:
http://www.usarmymodels.com/MANUFACTURERS/Italeri/italeri225.htmlHope this helps.
Roy