I was going through a box of my dads old stuff this morning and ran across this item. I googled the etching I could read on the bayonet which is: US M4. From what I could tell through internet research, this bayonet was issued during WWII, Korea, and possibly in Vietnam as well. My dad wasn't in any of these wars so I assume it belonged to my Grandfather who was in WWII. I was hoping to perhaps confirm the timeframe and issue of this bayonet. I apologize if I'm out of my lane posting this. Also, thanks for the great site.