It seems that you are not alone. I found an old auction with one like yours. US, 1943, JQMD, inspectors initials E.N.S.

US CAVALRY M1903 SPRINGFIELD RIFLE SCABBARD JQMD 1943

The Jefferson Quartermaster Depot made all kinds of leather goods for the military.

Your scabbard is about as late as they come, I think most of the cavalry was "dismounted" in 1943.