Why U.S. Govt Still Making 03/A3's in 1944?

[Hammer]

I sincerely appreciate everybody’s information and education. This all may be long known news for y’all, but it’s all new to me and it’s fascinating information for me.

I purchased this Remington in 1990 from an Army officer who said he had bought it years earlier from a national guard armory sales to military members transfer type program if I remember correctly.

So it looks like the receiver was made in late 42 or early 43 and then it got one of the replacement barrels that was made in August 1944. Of course now I wonder why they had to replace the barrel? Either it was used stateside for training and its original Barrel just got worn out from firing so many rounds at training ranges, or it was damaged or worn out from use overseas in wartime use. I think it was probably the former, but will never know.