To add to Jim's reasons, If the buckles are steel as they appear to be, I don't believe steel hooks/ends were being used in 1942, they still should be brass. The earliest I've see steel ones is in 1944. Also the rivet heads are not ground flat/flush as originals are. Do the smell test. Newer leather will still retain some what of a leather smell. A 1944 sling will have either no smell or a musty smell, although sometimes leather dressing that has been applied recently may hide the newer smell. Ray