Hi 8mm06......welcome to TFF!
Your Newton might not be in .30-06.....the caliber .30 gov would normally be .30 Government, also known as .30 U.S., but better known as .30-40 Krag. This was the caliber of the U.S. Krag-Jorgenson rifles we used in the Spanish-American war, before the adoption of the 1903 Springfield in caliber .30-06.
Problem is.....neither the Blue Book, nor The Standard Catalog of Firearms lists any Newton rifle made in .30 Government.
The Newton rifles listed are in calibers .22 Newton, .256 Newton, .30 Newton, .30 Adolph Express, .35 Newton, and .30-06.
Is the marking on the barrel "Newton Arms Co., Buffalo, NY" or "Buffalo Newton Rifle Corp., New Haven, Conn"?