I have one that is very similar to that except mine had a sling swivel inlet into the stock, the barrel has been changed at some point. Seems to be a common replacement barrel, as mine is very close to 22" and has that same Springfield site.  Makes it less desirable as a collectible carbine and affects the resale value.  But still a really nice rifle. Don't sweat the details as it will never be original so just enjoy it. I bet it shoots really nice. Its likely not a DCM rifle, but you never know......